Move `BridgeExitHash` in `interop`

[Freyskeyd]

Description

Move the BridgeExitHash from provers repo to interop: https://github.com/agglayer/provers/pull/140/files#diff-038ff527672af7e0d901d2c2abef00e402c158688cab4d0e5cbfbe5b2c8fd594R4