Add database migration for column "cosmos_network" to starry_roles table

[mikedotexe]

As StarryBot grows, we'd like to allow cw20 and cw721s from other Cosmos networks, or even different layer 1s. We want to make sure we're connecting to the right RPC, and it'd be best to have a cosmos_network column that could help us connect to the right network and ensure we've Bech32-encoded the wallet address properly.