Add possibility to check for available builds

[danmyway]

Is your feature request related to a problem? Please describe.
Add a sub-command (e.g. what) for both modules to query for available builds to test.

Describe the solution you'd like
tesar test copr|brew c2r|leapp-repository what will query for available copr|brew builds.
Ideally, use pagination to not spam the output.

[github-actions]

Hi, there.

Thank you @danmyway for suggesting this. Someone will take a look at this shortly.

---

This is an automated comment created by the peaceiris/actions-label-commenter. Responding to the bot or mentioning it won't have any effect.

[danmyway]

Add possibility to use reference to narrow the results returned.
Return also build ID/task ID to be able to specify the builds directly.

NOTE: Specifying the builds directly works fine for COPR builds, however for brew builds one must match correct task ID to correct RHEL version, thus might not work as intended.