Allow beakerlib libraries with partially clashing repo and name

[LecrisUT]

The original code should already have allowed for libraries with different name part but same repo, but as shown in practice that did not happen. This is because the string construction in of str(Beakerlib) only took the last part of the name, disallowing /foo/common, /bar/common. But beakerlib does not seem to actually have that restriction afaict.

Summary of changes:

• Reworked how the library's repo are cloned allowing for a big degree of collision
• Allow for whole libraries to collide and take the first definition Postponed
• Adjust the order of library fetching to account for the relaxed condition above Postponed
• Moved the non-existing-url handling to the git_clone utility
• Adjusted the display of the beakerlib library to display the full (repo)/(name) as it would be used in rlImport

Pull Request Checklist

• implement the feature
• extend the test coverage Postponed, only example right now of the failure in Library conflicts with different url #4440 is in kernel repo which is too slow to use, need to create one in tests repo (Add a beakerlib test case for tmt#4440 tests#23)
• include a release note

Depends on #4499
Closes #4440

[psss]

Seems there are some failing tests:

Library 'openssl/certgen (https://github.com/beakerlib/openssl)' conflicts with previously fetched 'openssl/certgen (https://github.com/beakerlib/openssl#master)'.
:: [ 13:55:37 ] :: [   FAIL   ] :: Command 'tmt run -arvvvddd plan --name 'rpm|fmf|nick|duplicate'' (Expected 0, got 2)

[LecrisUT]

Seems there are some failing tests:

Library 'openssl/certgen (https://github.com/beakerlib/openssl)' conflicts with previously fetched 'openssl/certgen (https://github.com/beakerlib/openssl#master)'.
:: [ 13:55:37 ] :: [   FAIL   ] :: Command 'tmt run -arvvvddd plan --name 'rpm|fmf|nick|duplicate'' (Expected 0, got 2)

Let's postpone this one. The test failures are related to the feature that I was planning to address later one, but it seems I cannot fix the tests without that feature.

• Allow for whole libraries to collide and take the first definition Postponed

• Adjust the order of library fetching to account for the relaxed condition above Postponed