feat: add KnownCaipNamespaces.Bip122 for Bitcoin family

[ccharly]

Adding a new known CAIP namespace for Bitcoin.

You can find a proper BIP-122 CAIP 2 identifier here:

• https://github.com/ChainAgnostic/CAIPs/blob/main/CAIPs/caip-2.md#test-cases

We could also update the for KnownCaipNamespaces to match those test cases but the test as-is seems good enough AND future-proof too.