[WIP] Support Celo native's credit and debit gas fee functions

[martinvol]

• [x] Add modifier so that only vm can call
• [x] Add modifier so that it can only be called on Celo (by checking Celo Registry address has bytecode)
• [x] Add credit and debit functions
• [x] Add Fundry tests
• [ ] Check with wormhole team how to refactor to comply with repo guidelines

[martinvol]

Yeah, makes sense.

My original intention with this PR was to pull it in front of your team so you could suggest me the better course of action.

Even if this code gets deployed only on Celo, I'd still include the checks to make sure the chain is actually Celo compatible.

[SEJeff]

@martinvol do you still want to work on this?

[djb15]

Closing as part of cleanup.