Allow main app plugin to work without palette

[vidartf]

Code changes

Changes the dependency of various plugins on the Command palette from required to optional.

User-facing changes

Users can now disable the command palette without causing other core plugins to fail to activate.

Backwards-incompatible changes

Some of the plugins' activate function changes signature. This should probably be considered backwards incompatible, but could be considered non-breaking as well if we insist on the signature being dynamically defined by the required/optional keys.

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[jasongrout]

This should probably be considered backwards incompatible

So 2.0?

[vidartf]

So 2.0?

I wrote it that way because I wanted to have a discussion about this 😃

[afshin]

I think maybe the if (palette) {...} statements should all be consolidated into one.

We don't need to block on this, but this PR does need a rebase.

[blink1073]

@declanvk, look, auto-labels!

[afshin]

Thank you!

[afshin]

The CI integrity check failure is legit. You just need to run jlpm run lint and check in the changes. The console-extension and hub-extension index files need to be linted:

diff --git a/packages/console-extension/src/index.ts b/packages/console-extension/src/index.ts
index 22c14004b..655f4f8a9 100644
--- a/packages/console-extension/src/index.ts
+++ b/packages/console-extension/src/index.ts
@@ -104,7 +104,13 @@ const tracker: JupyterFrontEndPlugin<IConsoleTracker> = {
     IRenderMimeRegistry,
     ISettingRegistry
   ],
-  optional: [IMainMenu, ICommandPalette, ILauncher, ILabStatus, ISessionContextDialogs],
+  optional: [
+    IMainMenu,
+    ICommandPalette,
+    ILauncher,
+    ILabStatus,
+    ISessionContextDialogs
+  ],
   activate: activateConsole,
   autoStart: true
 };
@@ -650,7 +656,7 @@ async function activateConsole(
     // Add kernel information to the application help menu.
     mainMenu.helpMenu.kernelUsers.add({
       tracker,
-    getKernel: current => current.sessionContext.session?.kernel
+      getKernel: current => current.sessionContext.session?.kernel
     } as IHelpMenu.IKernelUser<ConsolePanel>);
   }

diff --git a/packages/hub-extension/src/index.ts b/packages/hub-extension/src/index.ts
index 864071c73..5c01e9944 100644
--- a/packages/hub-extension/src/index.ts
+++ b/packages/hub-extension/src/index.ts
@@ -36,7 +36,7 @@ function activateHubExtension(
   app: JupyterFrontEnd,
   paths: JupyterFrontEnd.IPaths,
   palette: ICommandPalette | null,
-  mainMenu: IMainMenu | null,
+  mainMenu: IMainMenu | null
 ): void {
   const hubHost = paths.urls.hubHost || '';
   const hubPrefix = paths.urls.hubPrefix || '';

[afshin]

Er, I just pushed those changed, never mind 😄

[vidartf]

Er, I just pushed those changed, never mind 😄

Sounds reasonable since you stole my commit hook lints back ;)