ISPN-3979 JdbcStringBasedStore loading of Key2StringMapper class is too
restrictive

* Key2StringMapper class is now loaded using ClassLoader from
* GlobalConfiguration
ISPN-4649 RemoveCommand does not activate the key in Passivation

* No tests added since ISPN-4559 tests cover this scenario
ISPN-4559 Replace fails with cache loader

* Tests all the conditional commands
ISPN-4657 Allow for customization of SearchWorkCreator used by the QueryInterceptor
ISPN-3938 AdvancedAsyncCacheLoader.process() concurrency issues

Simplify ExecutorAllCompletionService to track the tasks itself instead of
using an ExecutorCompletionService.