Add Assert assertions to Pester

[nohwnd]

Fix #1423
Fix #1316
Fix #1323
Fix #1355

PR Summary

This PR adds assertions from Assert module to Pester, to serve as a base for future assertions and to live side-by-side with the existing Should assertions that are based on parameter sets.

PR Checklist

• PR has meaningful title
• Summary describes changes
• PR is ready to be merged
  • If not, use the arrow next to Create Pull Request to mark it as a draft. PR can be marked Ready for review when it's ready.
• Tests are added/update (if required)
• Documentation is updated/added (if required)

[github-advanced-security]

PSScriptAnalyzer found more than 20 potential problems in the proposed changes. Check the Files changed tab for more details.

[fflaten]

We should probably decide on #2381 soon, so these assertions can either implement it - or not. 🙂

[nohwnd]

/azp run

[azure-pipelines]

Azure Pipelines could not run because the pipeline triggers exclude this branch/path.

[nohwnd]

Should be good enough to release in 6.0.0-alpha1 so we can get other people to look at this. Please give at another quick review @fflaten .

[fflaten]

With 7k linediff I can't promise "quick", but I'll try tomorrow when my browser is done rendering the diff. 🙂 I'll trust your tests for functionality.

[fflaten]

Great work! 🚀 I left some comments, some of which should be addressed before alpha.

I haven't tested these manually and only skimmed through the tests for now. Wouldn't be able to find missing testcases on such a large PR tbh. and it looks like you've covered the basics.

[nohwnd]

I've fixed all the suggestions, and what I did not fix I moved to issues :) Pls approve.