Improve readonly editor behavior

[msujew]

What it does

Improves our readonly handling for monaco editors (editors can now dynamically change being readonly and writable).

Additionally adds a readonly mode to notebook editors. This new readonly mode disables a lot of notebook features:

• Editing (code & markdown)
• Execution
• Drag & drop
• Creating new cells

This change lays the groundwork for a few features in the collaboration feature (where readonly can be toggled) and the changes required for #13353.

How to test

1. Open a monaco editor (or notebook editor).
2. Run the command Toggle File System Readonly. It toggles whether the file URI scheme is treated as readonly.
3. Play around with the editors. You should not be able to manipulate the editors.
4. Open a new editor. It should open in readonly mode.
5. Run the command again. Everything should work as normal.

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines

[jonah-iden]

is this intended to not work for new not yet saved files? it makes sense since they are not yet in the filesystem. I just want to make sure

[jonah-iden]

Also seems like there is an regression. When creating new markdown cells you get following error in the console and its not possible to edit them anymore. Even when readonly is disabled

Uncaught Error Error: MISSING extHostDocument for notebook cell: vscode-notebook-cell:/c%3A/Typefox/Open_Source/theia_test_workspace/notebooks/test-notebook1.ipynb#W2sZmlsZQ%3D%3D%20
    at deserialize (c:\Typefox\Open_Source\theia\packages\core\src\common\message-rpc\rpc-message-encoder.ts:184:106)
    at read (c:\Typefox\Open_Source\theia\node_modules\msgpackr\unpack.js:424:1)
    at readObject (c:\Typefox\Open_Source\theia\node_modules\msgpackr\unpack.js:522:1)
    at recordDefinition (c:\Typefox\Open_Source\theia\node_modules\msgpackr\unpack.js:992:1)
    at read (c:\Typefox\Open_Source\theia\node_modules\msgpackr\unpack.js:418:1)
    at checkedRead (c:\Typefox\Open_Source\theia\node_modules\msgpackr\unpack.js:197:1)
    at unpack (c:\Typefox\Open_Source\theia\node_modules\msgpackr\unpack.js:104:1)
    at decode (c:\Typefox\Open_Source\theia\node_modules\msgpackr\unpack.js:176:1)
    at decode (c:\Typefox\Open_Source\theia\packages\core\src\common\message-rpc\rpc-message-encoder.ts:163:29)
    at parse (c:\Typefox\Open_Source\theia\packages\core\src\common\message-rpc\rpc-message-encoder.ts:167:21)
    at <anonymous> (c:\Typefox\Open_Source\theia\packages\core\src\common\message-rpc\rpc-protocol.ts:88:93)
    at <anonymous> (c:\Typefox\Open_Source\theia\packages\core\src\common\event.ts:170:42)
    at invoke (c:\Typefox\Open_Source\theia\packages\core\src\common\event.ts:178:26)
    at fire (c:\Typefox\Open_Source\theia\packages\core\src\common\event.ts:321:36)
    at handleData (c:\Typefox\Open_Source\theia\packages\core\src\common\message-rpc\channel.ts:255:38)
    at handleMessage (c:\Typefox\Open_Source\theia\packages\core\src\common\message-rpc\channel.ts:209:29)
    at <anonymous> (c:\Typefox\Open_Source\theia\packages\core\src\common\message-rpc\channel.ts:167:61)
    at <anonymous> (c:\Typefox\Open_Source\theia\packages\core\src\common\event.ts:170:42)
    at invoke (c:\Typefox\Open_Source\theia\packages\core\src\common\event.ts:178:26)
    at fire (c:\Typefox\Open_Source\theia\packages\core\src\common\event.ts:321:36)
    at handleMessages (c:\Typefox\Open_Source\theia\packages\plugin-ext\src\common\rpc-protocol.ts:255:39)
    at <anonymous> (c:\Typefox\Open_Source\theia\packages\plugin-ext\src\common\rpc-protocol.ts:199:49)
    at <anonymous> (c:\Typefox\Open_Source\theia\packages\core\src\common\event.ts:170:42)
    at invoke (c:\Typefox\Open_Source\theia\packages\core\src\common\event.ts:178:26)
    at fire (c:\Typefox\Open_Source\theia\packages\core\src\common\event.ts:321:36)
    at <anonymous> (c:\Typefox\Open_Source\theia\packages\plugin-ext\src\hosted\browser\hosted-plugin.ts:369:42)
    at <anonymous> (c:\Typefox\Open_Source\theia\packages\core\src\common\event.ts:170:42)
    at invoke (c:\Typefox\Open_Source\theia\packages\core\src\common\event.ts:178:26)
    at fire (c:\Typefox\Open_Source\theia\packages\core\src\common\event.ts:321:36)
    at postMessage (c:\Typefox\Open_Source\theia\packages\plugin-ext\src\hosted\browser\hosted-plugin-watcher.ts:36:32)
    at onRequest (c:\Typefox\Open_Source\theia\packages\core\src\common\messaging\proxy-factory.ts:166:49)
    at <anonymous> (c:\Typefox\Open_Source\theia\packages\core\src\common\messaging\proxy-factory.ts:145:80)
    at handleRequest (c:\Typefox\Open_Source\theia\packages\core\src\common\message-rpc\rpc-protocol.ts:232:39)
    at handleMessage (c:\Typefox\Open_Source\theia\packages\core\src\common\message-rpc\rpc-protocol.ts:104:26)
    at <anonymous> (c:\Typefox\Open_Source\theia\packages\core\src\common\message-rpc\rpc-protocol.ts:88:66)
    at <anonymous> (c:\Typefox\Open_Source\theia\packages\core\src\common\event.ts:170:42)
    at invoke (c:\Typefox\Open_Source\theia\packages\core\src\common\event.ts:178:26)
    at fire (c:\Typefox\Open_Source\theia\packages\core\src\common\event.ts:321:36)
    at handleData (c:\Typefox\Open_Source\theia\packages\core\src\common\message-rpc\channel.ts:255:38)
    at handleMessage (c:\Typefox\Open_Source\theia\packages\core\src\common\message-rpc\channel.ts:209:29)
    at <anonymous> (c:\Typefox\Open_Source\theia\packages\core\src\common\message-rpc\channel.ts:167:61)
    at <anonymous> (c:\Typefox\Open_Source\theia\packages\core\src\common\event.ts:170:42)
    at invoke (c:\Typefox\Open_Source\theia\packages\core\src\common\event.ts:178:26)
    at fire (c:\Typefox\Open_Source\theia\packages\core\src\common\event.ts:321:36)
    at messageHandler (c:\Typefox\Open_Source\theia\packages\core\src\browser\messaging\ws-connection-source.ts:156:54)
    at Emitter.emit (c:\Typefox\Open_Source\theia\node_modules\@socket.io\component-emitter\index.mjs:136:1)
    at emitEvent (c:\Typefox\Open_Source\theia\node_modules\socket.io-client\build\cjs\socket.js:519:1)
    at onevent (c:\Typefox\Open_Source\theia\node_modules\socket.io-client\build\cjs\socket.js:506:1)
    at onpacket (c:\Typefox\Open_Source\theia\node_modules\socket.io-client\build\cjs\socket.js:474:1)
    at Emitter.emit (c:\Typefox\Open_Source\theia\node_modules\@socket.io\component-emitter\index.mjs:136:1)
    at <anonymous> (c:\Typefox\Open_Source\theia\node_modules\socket.io-client\build\cjs\manager.js:237:1)

[msujew]

Also seems like there is an regression. When creating new markdown cells you get following error in the console and its not possible to edit them anymore. Even when readonly is disabled

The error is unrelated to the issue, but I fixed both. The error logged was actually due to a race condition in the notebook plugin frontend.

[msujew]

is this intended to not work for new not yet saved files? it makes sense since they are not yet in the filesystem. I just want to make sure

Yes, they use the untitled uri scheme, so they're unaffected by the command that toggles the readonly editors. It only toggles the readonly mode for files with the file scheme. Not necessarily intended, but in line with expectations.

[jonah-iden]

Thanks for fixing the race condition. Code looks good to me so approved