Fixes #94673

Part of #91606

#77131

For #77131

- Rename `onDidEdit` to `onDidChange`
- Allow custom editors to fire a `CustomDocumentContentChangeEvent` that only marks the editor as dirty but does not enable undo/redo. The only way for editor to get out of this dirty state is to either save or revert the file

For #94637

Allows the active paramter to be be specified per signature instead of for all signatures. If provided, this overrides `SignatureHelp.activeParamter`

Fixes #93852

fixes #90499

Fixes #91606

For #77131

Fixes #93963
Fixes #94515
Fixes #94517
Fixes #94527
Fixes #94509
Fixes #94514
Fixes #93996
Fixes #93913

This removes explicit edits from the API and reshapes the API to more closely match VS Code's internal API. The change also tries to better express the lifecycle of backups

Create a temporary overload for testing `CustomEditor`. In finalization, we'd update `registerCustomEditorProvider` to take both types of custom editor instead

For #77131

The team would like to discuss this API further before finalizing it. `CustomTextEditor` will still be finalized this iteration

Fix #93815

Fixes #94061

Fix #93618

For #77131

#85992

This reverts commit 51a62012.