Ensure preference files only in problems view if open

[colin-grant-work]

What it does

Fixes #7154 by disposing of the preference system's reference to the MonacoEditorModel when not in use. This is similar to VSCode's approach in which the model reference is disposed of at the end of the write.

How to test

1. Open the application
2. Open the problems view
3. Open a preference file
4. Ensure that the preference file has some problems (dangling commas, schema violations)
5. Close the file
6. Observe that the problems view does not continue to show the problems for the preference file when it is closed.

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1. Do normal preference operations (set values in the UI, set values in the file)
2. Observe that the changes take effect as expected.

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

[msujew]

The changes look really good to me 👍

The editor reference seems to be disposed as expected, removing the associated problems. As a consequence, the problems view isn't polluted with any configuration related issues.

I'll let others review as well.

[vince-fugnitto]

The changes look good to me 👍

• confirmed the markers in the settings.json file only appear if the file is opened (similarly to vscode) so there is no noise on startup in the problems-view
• confirmed that markers in the settings.json file are properly populated (ex: dangling commas, invalid preferences)
• confirmed that updating preferences take effect like today

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I noticed #10599 when testing but I confirmed that it also exists on master.

[colin-grant-work]

@vince-fugnitto, I couldn't come up with a better solution to flakiness of these tests than just extending the timeout, and that seems to have gotten it through CI, at least. If you're OK with that, I'll write up breaking changes from this PR and merge it this week.

[colin-grant-work]

@msujew, just want to confirm your (infomal) approval stands here?

[msujew]

@colin-grant-work Yep, still stands :)

I did a brief look over the changed code and performed another look at the App running with your changes. Everything is still looking good 👍

[Okon199]

Please help I'm working through alot