WANObjectCache: Change getWithSetCallback() signature to key/ttl/callback/opts

WANObjectCache: Change getWithSetCallback() signature to key/ttl/callback/opts

* Put 'checkKeys' param in opts array instead of as a separate parameter.
  It's neat to not have to skip unnamed/positional arguments that are optional.
* Move TTL to be before callback instead of after. This avoids dangling integers
  toward the bottom of a large code block that have no obvious meaning.
  Matches BagOStuff::getWithSetCallback.

Add unit test for lockTSE to confirm

Change-Id: I60d6b64fc5dff14108741bafe801fd1fde16d1df