Add a method to clear cached variants from SearchVariant, and a configuration flag for whether
a variant should be enabled or not. Add a FullTextSearch TestState class which will globally
disable the queuedjobs and fulltextsearch shutdown handlers during tests, and is not used to
clear cached variants on each test to prevent global state leakage.
Also removes Phockito as a test dependency.
When the module was called solr we could call SearchUpdater::bind_manipulation_capture in _config.php, because
solr/_config.php was included after mysite/_config.php. This isnt true when the module is called fulltextsearch
Instead we hook into the new RequestProcessor in 3.0 to make the manipulation capture. We also make
bind_manipulation_capture re-callable, so you can call it any time you need to make sure.