AggLayer: store token name in faucet storage

[mmagician]

The AggLayer faucet currently stores token symbol and decimals but not the full token name. The token name is needed to:

1. Compute the metadata hash on-chain: keccak256(abi.encode(name, symbol, decimals))
2. Enable future on-chain verification of the metadata hash during faucet registration

Related work: PR #2439 (Token Metadata extension to form standard) adds token name to the standard faucet metadata. Once that lands, the AggLayer faucet should use it.

Context: #2453, PR #2583