Fix membership tests (add -and)

[MichelZ]

PR Summary

Membership tests lack "-and" operator. I did occasionally get wrong results like this:

Context Test-VSTeamMembership
      [-] Should test membership 18ms
        Expected Invoke-RestMethod in module VSTeam to be called 1 times exactly but was called 2 times
        22:             Assert-MockCalled Invoke-RestMethod -Exactly 1 -ParameterFilter {
        at <ScriptBlock>, C:\MIZE\DEV\GitHub\vsteam\unit\test\membership.Tests.ps1: line 22

PR Checklist

• [-] Write Help
• [-] Write Unit Test
• [-] Update CHANGELOG.md

(No need for those)

[DarqueWarrior]

We will just roll them into the next release.