Improve Windows Dev Experience: fix npm commands (cross-env package), fix Source Control Repos, and document all

[KetchupOnMyKetchup]

Resolves #89

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Fix so that npm commands to work in Windows:

1. Add cross-env package to vscode main project
   • Note though this package is Public Archive, it is still being actively maintained "NOTICE: cross-env still works well, but is in maintenance mode. No new features will be added, only serious and common-case bugs will be fixed, and it will only be kept up-to-date with Node.js over time."
   • cross-env is "finished" (now in maintenance mode) kentcdodds/cross-env#257
2. Escape with slashes in package.json: format, format-check, and test

Updates to Contributing.md doc

1. Reorganize and rewrite the Dev loop & Testing changes section to be more clear
2. Note use of cross-env package
3. Removing $ from commands to make copy/paste easier and indicate it works on Windows as well
4. Add specific notes about which directory to run npm commands
5. Add instructions and screenshot for adding both repos to Source Control Repositories

Fixed Source Control Repositories (before it only showed vscode-github-actions and not language services), figured out from this issue:

Screenshots from Windows BEFORE changes (broken state):

Screenshots from Windows to show that it works still after changes:

Screenshots from Mac to show that it works still after changes:

[jtamsut]

Left a few non-blocking questions/comments