Feature: port Amadevus/pwsh-script module

[amis92]

@ebekker I tried my best to port in my module in the form I have in my repo. There's a lot of changes, and still a lot to do. Please take a look and tell me what are the next steps.

I see the following:

• I use default vs-code format document on ps1 files which differs from original formatting (introduces unnecessary noise)
• Set-ActionFailed definitely requires discussion 😅 your implementation doesn't work for my use case in pwsh-script, but mine doesn't work in general case; I'd want to be able to still "catch" the error message and set it as an output. Ideas?
• My Add-ActionSecret follows the core toolkit naming (core.addSecret)
• My Invoke-ActionGroup follows the core toolkit naming (core.group)
• In build-docs.ps1:
  • I made the script executable
  • I used script block instead of string to have IntelliSense available in it
  • I purge the directory before writing files
• I added a couple new commands:
  • Get-ActionIsDebug
  • Invoke-ActionNoCommandsBlock
  • Send-ActionCommand (surfaced, as I feel it's useful, new commands are added almost constantly)
  • Set-ActionCommandEcho
• Replaced tests with my own; this will probably need much more work to merge both suites.