feat(AztecMacro): Correct serialized size computation for shared state

[LHerskind]

The macros are currently not handling the shared state sizing correctly when assigning storage slots.

For the SharedImmutable it should be fairly straightforward. When #4738 is implemented, it should be handles similar to public state.

However, when implementing the shared mutable storage (#4761) the type of storage will be storing N*2 + 1 value to state, and not just the N that the type T would normally have.

This is to account for the before and after.

This means that the computation needs to be altered slightly, to ensure that we don't end up overwriting the storage by mistake.

[Thunkar]

For SharedImmutable wouldn't it be possible to just hash the current storage slot, just like we do with maps?