This also lifts a bunch of logic from smack-websocket-okhttp into
smack-websocket. Furthermore, the following subprojects require now
Java 11:
- smack-integration-test
- smack-omemo-signal-integration-test
- smack-repl
- smack-websocket-java11
Related tracking issue: SMACK-835
The before/after class annotations are now no longer borrowed from
JUnit.
Also some integration tests used @After and/or @Before from JUnit,
which was never supported nor had any effected. Those methods got
deleted. But since there appears to be a desire for such a
functionality in sinttest, we should consider adding one.