Add/test Github codespaces

[DonRichards]

Suggestion:

Enable codebase and test it here before rolling out it to other repos.

https://docs.github.com/en/codespaces/overview

What does this do

Adds as a VS Code editor to navigate/view code and (most interestingly) spin up an on-demand sandbox for the user. This includes the ability to specify a web URL to access to test the build. This feature won't help much in this repo but will in ISLE-dc. Github's video demo on this is here.

Suggested Purpose

• Sandbox for testing
• Automate linting/testing (not a CICD workflow, intended for built in plugins like intellisense)
• Constant environment for testing/debugging/review for deployments.