Add SET constraintCheckTime

which forwards to the TransactionService, which ignores it for Persistit. In FDB, this will do something. (Request coming there very soon.)

I tried to strike a balance between flexibility (e.g. Properties) and rigidity (base system knows all the FDB-specific settings). I could probably be pushed in either direction if someone has a better model.

Clean up handling of allowed SET options, which was getting kinda large and still had newtypes in it. I did not remove newtypes as an "engine" type because that would make the diff even larger and this was already the bulk of it. Note that there is a new SET option whose only purpose is to make the statement cache test work because it wants to test something that is a cache key and OutputFormat means that all its test results are JSON. Turns out newtypes was filling this role.