encapsulate FS logic

[lifeart]

we need to encapsulate all fs logic into one place, to get ability to swap it if needed

https://code.visualstudio.com/api/references/vscode-api#FileSystem

Usecases:

• https://github.com/NullVoxPopuli/limber/blob/main/packages/monaco/preconfigured/index.ts#L45
• https://docs.github.com/en/codespaces/the-githubdev-web-based-editor (press . in any repo)

https://code.visualstudio.com/docs/remote/codespaces#_why-is-an-extension-not-installable-in-the-browser

Web extension limitations

Related:

• figure out ability to get http-based LS connection  #276

Action items:

• create FS provider encapsulate LS file-system acces logic into FS provider #303
• rewrite logic for async fs access encapsulate LS file-system acces logic into FS provider #303

cc @NullVoxPopuli