[theming] changing themes quickly results in a dialog

[vince-fugnitto]

Description

Using #6475, if a user changes themes quickly, a dialog is displayed that there is inconsistency in the global settings.json in the editor and on the filesystem (auto-save is off)

Steps to Reproduce

1. using VS Code like theming (colors and icons) #6475, attempt to change the color theme quickly.
2. a dialog appears that there are unsaved changes in the settings.json.

[akosyakov]

I don't think it can happen often, does it? I had hard time to reproduce it.

[akosyakov]

but it breaks tests from time to time, i.e. #5774 failing because of it

[akosyakov]

Oh, basically we need to reimplement logic from the monaco editor model to handle concurrent updates for resource. I think we are better to rewrite AbstractResourcePreferenceProvider with the monaco editor model instead of using the resource directly as @vince-fugnitto were suggesting in another PR. In such implementation if there is no opened editors for such resource we will trigger auto save, otherwise rely on a user to save the dirty preference editor.

[akosyakov]

That's tricky:

• the editor model cannot be acquired if editor preferences are not ready, so there is a cycle
• it breaks preference tests, since it requires Monaco

I think we can do it after #6409 that we can port tests to run within the app.

[akosyakov]

KeymapsService suffers from the same problems

[akosyakov]

It should be fixed with #7110. @vince-fugnitto could you try?