Improve identifiers quotation logic for all providers

[MaceWindu]

Right now for some providers we don't have proper quotation logic, which could lead to incorrect sql.
It is not an issue for most of users, as nobody generally use identifiers that require better quitation logic than we have now, but still from time to time we get reports like that: linq2db/LinqToDB.Identity#15, linq2db/LinqToDB.Identity#16