Add option to disable v5 syntax

[nohwnd]

Add option to disable Should -Be and other assertions shipped with Pester v5, so when you migrate you don't accidentally regress.

Fix #2495

[nohwnd]

I am stupid, why is this a.b test writing error to the pipeline, I thought it is because Verify-Equal outputting the $actual (which it does), but now I give it only the message, and still it shows the error. No other test does this, and the code looks the same.

[nohwnd]

It must be the CI format, because it formats the output to be recognized by azdo.