Test: Code Actions on Save Behavior

[justschen]

tests candidate for #194861.
insiders PR (when released): #194870
release branch PR: #194930

Things to test:

1. Search in settings for Code actions on save
2. edit in settings.json
3. Test scenarios for explicit, always, and never when saving normally, and do so again when Auto Save is enabled for Window change and Focus Change, as well as when Auto Save is enabled after delay (in which case nothing would happen).
4. Test scenarios for true and false in same conditions.
5. Code Actions with the array (ensure no error, runs like true and false).
6. Edge Cases: Scenarios like ESLint codeActionsOnSave not work #194978 where multiple types of source actions are used.

Example for arrays:

"editor.codeActionsOnSave": [
    "editor.formatOnSave",
    "source.organizeImports",
    "source.sortImports",
    "source.fixAll"
  ]

Runs when code actions are in the array, does not run when code actions are excluded from the array.

Known issues:

• Intellisense only shows source.fixAll and source.organizeImports: Provide better completion for editor.codeActionsOnSave #161284