Get VS Code extension available in online editors

[tatomyr]

What should we improve?

At the moment, our extension isn't working in online editors.
However, Github Codespaces is essentially a an online VS Code emulator, so it should support using our extension.

How should we improve it?

• Investigate what is missing
• Define "browser" entry point in package.json
• Substitute process and path global vars
• Use vscode specific fs
• Use browser version of Language Server Protocol
• Test in vscode.dev: https://code.visualstudio.com/api/extension-guides/web-extensions#test-your-web-extension-in-on-vscode.dev
• Update other libraries if needed (we may need to update Redocly CLI somehow since it extensively uses fs)

Describe alternatives you've considered

None

Additional context

See this article for more details on developing extensions for Github Codespaces.

[tatomyr]

Here is the general info about extensions in vscode-web.

According to this guide a web extension should have "browser" field defined in package.json (alongside "main" field).
This should enable the extension in https://vscode.dev/ environment.

Here is the list of requirements to the web extension.
We already cover most of them.
However, we have to substitute process and path global variables; file system API should go through vscode.workspace.fs; use browser version of Language Server Protocol.

[tatomyr]

It appears it could be tested locally with --extensionDevelopmentKind=web flag. See more details here.

[roman-sainchuk]

Here are some details about testing web extension before publishing.

[roman-sainchuk]

We made language server browser-compatible and moved it to separate repository