Pay NEAR storage fees during the finalization

[sept-en]

Now there's a burden for users or us to pay NEAR storage fees to be able to receive the finalization transaction correctly.
Usually, this is ok and being handled by Rainbow Bridge UI, but sometimes when a new token is added and being transferred let's say to the receiver (let's say aurora for example) didn't pay the storage fee before so the proof is used but the transaction didn't succeed.

In our case we can check if the storage is registered for the given account and register it, paying the fee by the event-relayer account. There are some cons that someone could create a bunch of different tokens in order to drain the balance of the event-relayer account, but I don't expect this will happen as there's a requirement to put ~3.5 NEAR for the initial token bridging which is far more than the storage fee required to be paid for the transaction.

Also, as we already have a DB in event-relayer, we may cache if the storage fee is being paid for the specific token in order to reduce the number of additional calls related to the storage functionality.