[builtins] [proposed API] [vscode.markdown-language-features]: Theia misses proposed API: Document Paste

[marcdumais-work]

Bug Description:

Recent Markdown vscode builtin extension does not activate (see below). It looks like it's trying to use a proposed API that we do not support: "Document Paste": https://github.com/microsoft/vscode/blob/b25f6bf56c48d56fe59ae3fec641ed75c73a2980/src/vscode-dts/vscode.proposed.documentPaste.d.ts

I am currently encountering the issue testing pre-release vscode builtin extensions v1.72.2.

The example app pins this extension to a version that I think predates this API being used: 1.64.2

2023-04-18T16:02:13.527Z root ERROR [hosted-plugin: 220299] Activating extension 'Markdown Language Features (built-in)' failed: TypeError: i.languages.registerDocumentPasteEditProvider is not a function
    at t.registerPasteSupport (/tmp/vscode-unpacked/markdown-language-features-1.72.1.vsix/extension/dist/extension.js:1:1700637)
    at /tmp/vscode-unpacked/markdown-language-features-1.72.1.vsix/extension/dist/extension.js:1:1698626

Steps to Reproduce:

1.Replace the markdown-language-features extension with this pre-release one (v1.72.2):
markdown-language-features-1.72.1.zip
2. Start the example app (browser or Electron)
3. Look a the backlog log, confirm you see the exception from the Markdown extension, indicating failure of activation, like the one above

Additional Information

2023-04-18T16:02:13.341Z root INFO [hosted-plugin: 220299] PLUGIN_HOST(220299): PluginManagerExtImpl/loadPlugin(/tmp/vscode-unpacked/markdown-language-features-1.72.1.vsix/extension/dist/extension)
2023-04-18T16:02:13.527Z root ERROR [hosted-plugin: 220299] Activating extension 'Markdown Language Features (built-in)' failed: TypeError: i.languages.registerDocumentPasteEditProvider is not a function
    at t.registerPasteSupport (/tmp/vscode-unpacked/markdown-language-features-1.72.1.vsix/extension/dist/extension.js:1:1700637)
    at /tmp/vscode-unpacked/markdown-language-features-1.72.1.vsix/extension/dist/extension.js:1:1698626
    at t.activateShared (/tmp/vscode-unpacked/markdown-language-features-1.72.1.vsix/extension/dist/extension.js:1:1698668)
    at e.activate (/tmp/vscode-unpacked/markdown-language-features-1.72.1.vsix/extension/dist/extension.js:1:1755656)
    at async PluginManagerExtImpl.startPlugin (/home/<user>/theia/packages/plugin-ext/lib/plugin/plugin-manager.js:308:34)
    at async /home/<user>/theia/packages/plugin-ext/lib/plugin/plugin-manager.js:218:21
    at async PluginManagerExtImpl.$activatePlugin (/home/<user>/theia/packages/plugin-ext/lib/plugin/plugin-manager.js:270:13)
    at async Promise.all (index 0)
    at async PluginManagerExtImpl.activateBySingleEvent (/home/<user>/theia/packages/plugin-ext/lib/plugin/plugin-manager.js:265:9)
    at async PluginManagerExtImpl.$activateByEvent (/home/<user>/theia/packages/plugin-ext/lib/plugin/plugin-manager.js:249:13)

• Operating System:
• Theia Version: