Call onHide in MonacoContextMenuService

[colin-grant-work]

What it does

Fixes #11059 by fixing the MonacoContextMenuService to call onHide. Previously, it was returning the callback rather than calling the callback, resulting in this flag never getting reset, pushing us down this code path, resulting in the immediate disposal of any contributed code action items.

How to test

1. With this extension: code-action-demo-0.0.1.zip (source).
2. Open a plain text file.
3. Select any span of text.
4. A code action lightbulb should appear.
5. Click the lightbulb or hit CtrlCmd+.
6. Execute the test code action.
7. You should see a toast indicating that the code action was executed with the argument 'test'.
8. Repeat 3-7, and you should still be able to execute the code action successfully.

---

1. Checkout this branch
2. Run the API tests (yarn browser test)
3. They should pass.

The test on that branch doesn't work with the version of the TypeScript plugin we currently use - the code actions contributed by TS have a bug - so that branch is rebased on #11083 and uses vscode.typescript-language-features@1.62.3. I will make a separate PR for the test that can be merged once this PR and #11083 have been merged.

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

[vince-fugnitto]

The changes work well for me 👍