feat: state-key transformation w/ override

[ARR4N]

Why this should be merged

ava-labs/coreth has a partitioned state-address space, achieved by setting or clearing a specific bit in the hash used to key the space. This change allows such behaviour to be achieved with pure libevm instead of the StateDB wrapping that coreth currently uses.

How this works

Introduction of state.StateDBHooks interface, including a TransformStateKey() method that allows for arbitrary change of state key. If registered, this hook will be honoured by StateDB.{Get,GetCommitted,State}Key() methods unless they receive a stateconf.SkipStateKeyTransformation option.

How this was tested

Unit test of SetState() -> GetState() + GetCommittedState() round trip with and without options to skip.