refactor `SCBridgeWallet.validateUserOp`

[geoknee]

This only tries to extract a intermediarySig if it is required, meaning that a single 65 byte signature will still work if only a single signature is required.

Closes #109 , but not by using 130 byte signatures everywhere.

[NiloCK]

Q: Do refactors on the contract now mean that SCW addresses living in our ENV file will need to be recalculated?

[lalexgap]

Q: Do refactors on the contract now mean that SCW addresses living in our ENV file will need to be recalculated?

~Yup! We'll need to update the .env file with the new addressees.~ Hmm I thought this was the case but it seems the addresses are the same...