ISPN-4311 Do not try to be clever with file separators on Windows, just replace any backslashes with slashes
ISPN-4467 Fix BulkUtil formatting
ISPN-4467 Bulk get keys should use a compatibility collator

* Use a different collator when compatibility is enabled which makes
the necessary transformations from POJO to byte arrays.
ISPN-3938 AdvancedAsyncCacheLoader.process() concurrency issues

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