Finalize paste api and drop api tweaks

Fixes #30066

This finalizes the documentPaste api. This api allows extensions to attach metadata on text copy and change how content is pasted. Some examples:

- Updating imports for pasted code
- Inserting an image as an attachment in notebooks
- Pasting files converts them to relative text paths

extensions/ipynb/package.json

@@ -10,7 +10,6 @@
     "vscode": "^1.57.0"
   },
   "enabledApiProposals": [
-    "documentPaste",
     "diffContentOptions"
   ],
   "activationEvents": [