Script for transferring tokens across the bridge

Create a script like so:

```
hardhat bridge <sourceNet> <destNet> <accountPublicAddress> <amount>
```

And this just basically burns tokens on one side and mints them on the other. Perhaps this relies on the following env vars:

```
CONTRACT_ADDRESS_MAINNET_SEPOLIA=0xblah
CONTRACT_ADDRESS_OPTIMISM_SEPOLIA=0xblah
```