Add PasteEditProvider (#107283)

For #30066

This adds a new `documentPaste` api proposal that lets extensions hook into copy and paste.

This can be used to do things such as:

- Create link when pasting an image
- Bring along imports when copy and pasting code

extensions/markdown-language-features/tsconfig.json

@@ -7,6 +7,7 @@
 		"src/**/*",
 		"../../src/vscode-dts/vscode.d.ts",
 		"../../src/vscode-dts/vscode.proposed.textEditorDrop.d.ts",
-		"../../src/vscode-dts/vscode.proposed.dataTransferFiles.d.ts"
+		"../../src/vscode-dts/vscode.proposed.dataTransferFiles.d.ts",
+		"../../src/vscode-dts/vscode.proposed.documentPaste.d.ts"
 	]
 }