* Update definition of Promise in winjs.base.d.ts.

* Update to new Promise declaration

* Fix remaining errors.

Initialize extension host customers only after a connection has been established with the extension host; retire IThreadService

fixes #8809
fixes #24014

- Revert changes to id in Ext description. No lowering of name.
- Implement an equal function to check equality of extensions
- Use above function to check the equality with extension description

- In Extension description in Extension host
- In Extension enablement service
- Rename identifier to id in IExtension

allow users to toggle between git and preview SCM

related to #15558

- Include extension specific properties only
- Refactor: Move extensions scanning to MainThreadExtensionService

* Use the extension descriptions available in the UI thread
* Don't wait for handling extension points until extension host is running
* Create the extension host process only after extension points have been handled
* Send the initial configuration as part of the initData to the extension host