ADO changes to follow guidelines

[MiYanni]

Description

See the guidelines here: https://dev.azure.com/azure-sdk/internal/_wiki/wikis/internal.wiki?wikiVersion=GBwikiMaster&pagePath=%2FAzure%20DevOps%20Pipeline%20Guidance

Changes

• Moved yaml files to .azure-pipelines folder
• Moved core job logic to steps files in .azure-pipelines/util
• Removed install-pwsh steps since the Windows machines now have PowerShell Core installed
• Moved the after.Azure.PowerShell.sln.targets to tools so the build folder is no longer needed
• Used shared Repo.props values throughout the build.proj
• Removed duplicated and deprecated properties in build.proj
• Changed ADO build process to use a matrix to define the OS differentiation
• Changed ADO build process to have a netcoreapp21 (called powershell-core) and net472 (called windows-powershell) pipeline (based on test framework and intent)
• Made TestNet472 target use the Build target to run properly (same as Build and Test for netcoreapp21)

Checklist

• I have read the Submitting Changes section of CONTRIBUTING.md
• The title of the PR is clear and informative
• The appropriate change log has been updated
• The PR does not introduce breaking changes
• If applicable, the changes made in the PR have proper test coverage
• For public API changes to cmdlets:
  • the changes have gone through a cmdlet design review (Microsoft internal partners only)
  • the cmdlet markdown files were generated using the platyPS module

[weshaggard]

Looks like a number of these templates can be folded into the one yaml file to avoid some levels of complexity.

[MiYanni]

Since these are reused between different jobs in different pipelines, it makes sense to have a separate template. The primary issue is that you cannot template a job matrix. Meaning, I can't make a job template where a strategy is conditionally defined.

[weshaggard]

Yes that is one of the limitations of the templates. However I don't think that would be necessary if you had one matrix strategy for both and just control the framework as one of the matrix variables.

[weshaggard]

If this is a configuration you want to enable at queue time then you will need to remove it from here and put it only in the build pipeline variables tab.

[MiYanni]

This is not intended to be build-time variables. I use these simply as global variables to all jobs in the yaml. If there was a concept of hard-coded values (constants), I would have used them here. Also, it is convenient to have all values that may change in the future listed at the top of the file.