* 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.

this allows to drop elements from the files explorer as well as a tab in the editor to be dropped e.g. into an opened terminal to take the path of the resource

* have explicit methods for changing the scroll position (delayed/smooth vs now/direct) that bubble up to the editor internals.
* have all other clients of ScrollableElement not use smooth scrolling

Workbench theme customisation for forground tab colour of inactive group appears to be missing (fixes #27067)

Closing a tab using middle mouse button on the 'x' causes the tab to the right to also be clsosed (fixes #25529)

themes - get rid of tab.activeWithInactiveEditorGroupForeground and inactiveWithInactiveEditorGroupForeground