* Webview api

* Cleaning up markdown webview

* Hooking up dispose

* Fix some merge errors

* Use custom context key to show markdown title bar contributions

* Add basic on focus and on blur events

* Fixing find widget in webview

* Hookup _isDisposed

* Use new extension resource scheme to load markdown extension resources

* Documenting keep alive

Fixes #43379

Fixes #43138

**Bug**
Pinch opening should zoom in. Pinch close shoud zoom out. This is currently reversed

**Fix**
Invert the pinch direction. Only inverts pinches. Scrollwhell events should remain as-is: scroll up to zoom in scroll back to zoom out

- Custom view service to get tree item viewer
- Custom view service to register the data provider