Move custom meddlers and meddler initialization to a common repo

[goran-ethernal]

We had an issue where two components in different repos (cdk and zkevm-ethtx-manager) have their own initialization of meddler for sqlite, which were different for HashMeddler. aggsender introduced an additional logic in the HashMeddler for handling nullable hash fields, which zkevm-eth-txmanager did not have, so when cdk node was run with both eth-txmanager and aggsender, the eth-txmanager initialized meddler with its own custom meddlers, which resulted in unsuccessful saving of new certificates to the sqlite db, since meddler is a global instance in the app, and it can be initialized only once.