[Attributor] Make IntegerState more flexible

To make IntegerState more flexible but also less error prone we split it
up into (1) incrementing, (2) decrementing, and (3) bit-tracking states.
This adds functionality compared to before and disallows misuse, e.g.,
"incrementing" updates on a bit-tracking state.

Part of the change is a single operator in the base class which
simplifies helper functions that deal with states.

There are certain functional changes but all of which should actually be
corrections.