* debt - syncdescriptors for composite

* debt - syncdescriptor for baseeditor

* debt - syncdescriptor for quickopenhandler

* debt - remove asyncdescriptor

* debt - introduce editor.ts in browser namespace

* fix todos

* Add template system for tab descriptions. (#12965)

* Add a boolean flag to onConfigurationChanged to prevent updates during initialization.

* - Change configuration key to 'workbench.editor.tabSubtitle'.
- Change configuration type to the enum ['default', 'short', 'medium', 'long']
- Move path logic into FileEditorInput.
- Move configuration handling into GroupService/ITabOptions.
- Refactor duplicate path shortening logic.

* Don't consider empty-string descriptions during de-duplication. Don't show subtitle when all descriptions are identical.

* Minor fixes and documentation.

Refactors TextEditorOptions.fromEditor to a static method instead of an instance method. This method is only called after creation of the options object and currently requires using a weird cast in a few places