Break out Unit tests

[DarqueWarrior]

PR Summary

This PR breaks out all the tests to single function per file. It also removes the

InModuleScope VSTeam {
}

From all the tests so the module does not have to loaded to run the tests.

PR Checklist

• Write Help
• Write Unit Test
• Update CHANGELOG.md

[DarqueWarrior]

This will be merged once all the tests are ported. I created it no so I could have CI fire on macOS and Linux to make sure the unit test still pass there as well.

[SebastianSchuetze]

Do you want me to help on that PR?
Please also aware that you need to include applyTypes.ps1 in the unit tests where needed. I had it in my function for PR #283 in this line:
https://github.com/DarqueWarrior/vsteam/blob/569367270c697c60c581b276edcc07c61468fd9e/unit/test/Get-VSTeamBuildTimeline.Tests.ps1#L9

Maybe you want to outsource the includes into an extra file so possible needed includes are done within one ps1 file.

[SebastianSchuetze]

related #279