Use serverInitiatedProgress instead of custom notifications

[LDAP]

Is your feature request related to a problem? Please describe.
ltex-ls is using custom notifications for progress reporting.

Describe the solution you'd like
Replace it with the standard server initiated progress scheme of the LSP specification.
See microsoft/pyright#1268 for a analog discussion

ltex/progress, with progress 0.0 --> window/workDoneProgress/create + $/progress with kind begin
ltex/progress, with progress 1.0 --> $/progress with kind end

Additional context
Simplifies integration with non vscode-ltex clients.

[valentjn]

This is already done, just haven't pushed yet.

[LDAP]

I would like to reopen this issue (but I can't due to GitHub permissions).

I tested the 9.0.0 alpha and it seams that the specification for serverInitiatedProgress is not met.

I think currently the server is implementing clientInitiatedProgress insted. But in this case the progress should be initiated by LTEX-LS.

The specification requires the server to

• Initiate progress reporting using the window/workDoneProgress/create request.
• Report progress using the generic $/progress notification.

Additionaly,

• the title parameter should only briefly inform about the kind of operation being performed. (e.g. Checking document).
• The uri of the file should instead be part of the message parameter.
• see here

[valentjn]

The server didn't use client-initiated progress as the tokens used by the server notifications are not introduced by the client before the server notifications. Just the window/workDoneProgress/create request was missing for server-initiated progress. This is fixed now, as well as the progress title.

[LDAP]

Does work now with the LSP client for Sublime Text too.

[valentjn]

Fix released in 9.0.0.