Migrate wormholescan to use new SDK

Migrating Wormholescan to the newest wormhole-sdk

This document describes the code changes needed to be able to replace the old wormhole-sdk to the newest one

There are two steps that need to be done for the app to be able to run with the new wormhole-sdk:

Upgrade from ethers@4 to ethers@6: ethers versions are incompatible between them, we can't have both installed, and wormhole-sdk depends on v6. Doing this includes:
- replacing every occurrence of a BigNumber to a native JS BigInt, for most cases it's straight-forward, but BigNumber had the from() function that we'll need to implement manually.
- replacing the imports of the ethers functions to their new location, and replacing those that don't exist anymore with a manual alternative
- adapt the code for the new ethers Types
Replace every common function from the old sdk to the new sdk: old sdk functions won't work anymore because of the ethers upgrade, so they'll need to be replaced before the app can run. This includes:
- replacing every ChainId in the app to the new ChainId type from the sdk
- replacing every ChainId.Avalanche or CHAIN_ID_AVALANCHE to chainToChainId('Avalanche')
- replacing every parseVaa() with the new deserialize() method
- implement a new method to get the "Signed Vaa" info (signed guardians and signatures)

With those steps the app should be able to run. But, standard relayers transactions and non-api-vaa transactions (RPC transactions) won't work.

Making those work will need a refactor in all the RPCs/ethers code, which is the hardest step regarding this migration.