PR Summary

Implements an updated devcontainer specification for quickly bootstrapping the PowerShell development environment.

Users can use this devcontainer locally, or develop in Github Codespaces (free minutes for Github users).

• Updated to official .NET SDK Devcontainer (the team no longer supports PowerShell containers)
• Lifecycle scripts all written in PowerShell for easy updates/maintenance!
• Auto-Installs current .NET SDK per the global.json in the repository, reducing churn
• Bootstraps the environment per the current linux development documentation spec
• Supports Hot Reload Debug for SMA! (Modules not supported yet)
• Prebuilds in GitHub Codespaces for rapid access

Additional Setup Necessary by PowerShell Team

1. Codespace prebuilds must be enabled in the PowerShell repository. This enables a bot that performs the prebuilds and uploads them. As PowerShell is an open public project, there is no storage cost to these images.

As this is developer tooling only, this is a low impact/low risk PR.

Demonstration

You can test this PR by going to Codespace Creation for the upstream branch.

You can also demo a more typical user experience by:

1. Go to https://github.com/JustinGrote/_PR-PowerShell/tree/feature/devcontainer
2. Hit comma (,) on your keyboard or click + on the codespaces menu
   

PR Context

I, as a PowerShell contributor or someone new to PowerShell development, want to at a click of a button have an environment where I can immediately start building, testing, and contributing to PowerShell, whether that is local to my own machine, in Github Codespaces, or anywhere that devcontainers are supported.

PR Checklist

• PR has a meaningful title
  • Use the present tense and imperative mood when describing your changes
• Summarized changes
• Make sure all .h, .cpp, .cs, .ps1 and .psm1 files have the correct copyright header
• This PR is ready to merge and is not Work in Progress.
  • If the PR is work in progress, please add the prefix WIP: or [ WIP ] to the beginning of the title (the WIP bot will keep its status check at Pending while the prefix is present) and remove the prefix when the PR is ready.
• Breaking changes
  • None
  • OR
  • Experimental feature(s) needed
    • Experimental feature name(s):
• User-facing changes
  • Not Applicable
  • OR
  • Documentation needed
    - [ ] Issue filed:
• Testing - New and feature
  • N/A or can only be tested interactively
  • OR
  • Make sure you've added a new test if existing tests do not effectively test the code changed
• Tooling
  • I have considered the user experience from a tooling perspective and don't believe tooling will be impacted.
  • OR
  • I have considered the user experience from a tooling perspective and opened an issue in the relevant tool repository. This may include:
    • Impact on PowerShell Editor Services which is used in the PowerShell extension for VSCode
      (which runs in a different PS Host).
      • Issue filed:
    • Impact on Completions (both in the console and in editors) - one of PowerShell's most powerful features.
      • Issue filed:
    • Impact on PSScriptAnalyzer (which provides linting & formatting in the editor extensions).
      • Issue filed:
    • Impact on EditorSyntax (which provides syntax highlighting with in VSCode, GitHub, and many other editors).
      • Issue filed: