[push] Don't require preselected repositories if there is only one
[git] cleanup: remove unused param & method
[git tests] allow custom debug log categories in specific tests
[git tests] remove unused test classes
[git tests] move some mocks to git4idea: they are used only there
[git tests] remove unused methods
[git test] remove unneeded suppression
[git test] convert testng to junit
[push] add toString, clarify javadoc
[push] generify PushSupport with PushSource, PushTarget, and Pusher additionally with Repository
[push] shorten subject with ... if it is very long & make it larger
[push] use correct Repo class in validate
[push] Show proposed targets in the order defined by plugins

* Let PushSupport return the sorted List.
* Use the order of items in the list in the completion items comparator.
Fix test name