* wip 2

* use viewlet stubs

* fix layering issue

* fix saveState and contextmenus

* move context menu logic into panecomposite

* revert tasks.json

* tasks again

* add showHeaderInTitleWhenSingleView values

* patch tests

* some cleanup

* more cleanup

* start view

* merging conflicts

* fix title and dnd

* adding missing api surface to pane composite

* additional merge resolution

Fixes https://github.com/microsoft/vscode/issues/86328

Fixes #86209

Part of https://github.com/microsoft/vscode-remote-release/issues/1777

Part of https://github.com/microsoft/vscode-remote-release/issues/1869

For #81574

This applies the fix from #84878 to a number of other descriptor classes in our codebase

For #81574

See #84669 for details of the problem around strict function types. This change converts `SyncActionDescriptor` to use a static `create` function. This allows us to make the `create` function generic so that it can take the correct types for strictFunctionTypes

Part of https://github.com/microsoft/vscode-remote-release/issues/1778

Fixes https://github.com/microsoft/vscode-internalbacklog/issues/885

Readonly helps out with TS's type guards and is also a good best practice. Specifically, readonly strings/numbers have their literal type instead of a generic `string` | `number` type, which can help catch dead code and some common programming mistakes

Fix microsoft/vscode-remote-release#1426