**Problem**
Editors use the `supportsSplitEditor` property to enable/disable splitting. Even if splitting is disabled, you can still split an editor by dragging it to create a new copy.

**Fix**
For non-splittable editors, make dragging always just move the editor to a new group

* Renaming Close Unmodified to Close Unsaved
https://github.com/Microsoft/vscode/issues/44033

* Putting back action identifiers

Allow extensions to specify custom tree view resoure type

Fixes #44300

Upgrade to use web audio api in xterm.js

Extract shouldEnableDotCompletions

Extract getConfigurationForResource

Reorder methods

Format sig

We only want to swallow exceptions around the request itself

#44166

Part of #44302

Fixes #41415

Support theming of active line number

fixes #42139