remove kernel provider from core, adopt kernel service, merge kernel2 and kernel interface, extract context keys from kernel manager, make context key manager only for execution/cancellation

Part of #111756
Fixes #121684

cc @joaomoreno

This reverts commit 1292b973.

This reverts commit d6ddd586.

For #120675

* markdown-language-features: fix windows file uri

* refactor: use Uri.joinPath instead

Fixes #121504

Fixes #121654

Fixes #121602

Be sure to emit events from applyEdits even when an error occurs
Fix #121687

Fixes #121638

Fixes #121507