Refactoring `:e` options + support windows host

This is both a request/issue/discussion. I reimplemented :e option a while back to support both the tab completion and opening file on remote. I learned that a few days ago that vscode-remote support windows machine as remote, and the assumption I made here

https://github.com/VSCodeVim/Vim/blob/e7c5c70f9f5ebc79004bf86cd69a3b242e51b623/src/util/path.ts#L115-L116

is no longer valid.

Since I just worked on a feature on another extension that touches on path manipulation, I learned more about how to handle different edge cases and I am thinking to refactor the work I did here to support some new features for :e:

• Support :e and auto completion with *nix remoting into Windows

• Change the base directory of the :e for relative path to the workspace folder of the active editor (to be more like vim) than just the folder containing the active editor
  Local cases:

  • A folder /home/steven/Vim is opened in vscode, and the active editor is src/statusBar.ts. :e ./ should autocomplete contents in the directory of /home/steven/Vim instead of /home/steven/Vim/src.
  • A folder /home/steven/Vim is opened in vscode, and the active editor is an untitled document. :e ./ should autocomplete contents the directory of /home/steven/Vim/ instead of /home/steven/Vim/src/
    A folder /home/steven/Vim is opened in vscode, and the active editor is file outside of the workspace like /home/steven/.bashrc. :e ./ should autocomplete contents the directory of /home/steven/ instead of /home/steven/Vim -OR- No folder is opened, and the active editor is /home/steven/Vim/src/statusBar.ts, :e ./ should complete the contents in the directory of /home/steven/Vim/src/
  • No folder is opened, and the active editor is an untitled, only absolute path can be autocompleted

  Remote cases are the same as the local case except:

  • No folder is opened, and the active editor is an untitled, it can also autocomplete local absolute path.

• Remove auto extension completion when execute :e command (vim doesn't do that. I don't know why it was there in the first place - Maybe it was there because there wasn't any autocompletion)

  • This feature only auto completes using the active buffer's extension. For example: if I opened src/statusBar.ts and entered :e textEditor, vscode vim will tried to open src/textEditor.ts
  • AFAIK, this doesn't exist in regular vim, and doesn't make much sense now that we have auto completion.

I started part of the work, and just want to make sure those features/fixes make sense before I get to far.

Other related issues:
https://github.com/VSCodeVim/Vim/issues/4859

Start with src/util/path.ts at the linked lines and review related issue #4859. Trace the existing :e completion and remote-file handling before checking how workspace, active-editor, untitled, and Windows paths are resolved. Done means the listed local and remote cases work, and extension auto-completion is no longer added by :e.