Server-side processing injection use refactoring.

- CloseableService no longer requires injection for internal request processing usage.
- AsyncContext no longer requires injection for internal request processing usage.
- Factories providing injection of request-scoped types refactored to leverage the same RequestProcessingContext instance reference.
- Introduced thread-safe Ref support.
- Other minor refactorings.

Change-Id: Iadfd48a98b2c2f9ab144dfdf7678db5f3473c137
Signed-off-by: Marek Potociar <marek.potociar@oracle.com>