Fix test scope resources to not be added to the main scope

[Gedochao]

Supersedes #3879

@btomala I took your commits from #3879 and squashed them, to include the initial part of the fix & tests from your branch.
I will squash the whole thing when this PR gets merged.

TL;DR, what was happening:

• resource directories from the test scope were added to 2 spots unnecessarily
• one of those spots did not respect the scope, which caused the test scope resources to be on the main scope classpath
• the "unnecessary" code adding the resources the second time put them on the elements list of inputs, which was then used to watch those directories under --watch (and made them necessary)
  • this is tidied up in the other commit
• I added some more tests to cover some extra scenarios

[tgodzik]

LGTM Thanks @btomala for the contribution!

[btomala]

Thank you two for the smooth cooperation