Support Cursorless in vscode.dev

[pokey]

In order to make it easier for people to use Cursorless, we'd like to support Cursorless when VSCode is running in a web browser. The approach is roughly as follows:

• [ ] https://github.com/pokey/command-server/issues/13
• [ ] https://github.com/cursorless-dev/cursorless/issues/945
• [ ] https://github.com/cursorless-dev/vscode-parse-tree/issues/53 (though by this point we may be embedding parse tree extension in Cursorless via nx)
• [ ] Add support for Cursorless to bundle as a web extension

Note that if we have a proper lsp by this point, VSCode web supports this kind of thing; see the docs