Blockchain network compatibility accross libp2p protocols

[da-kami]

Currently it can happen that swap CLI user send BTC to a mainnet swap CLI, but the swap is rejected because the ASB runs on testnet. The BTC then sits in the swap CLI wallet until the user finds a mainnet ASB to swap with.
In the future this problem will be mitigated by implementing #513
Nevertheless, the blockchain network should be ensured for each libp2p protocol.

As discussed here #492 we should have a more complete way to ensure that both the swap CLI and the ASB are on the same network prior to a swap.
Instead of the check against the network in the spot price protocol all protocols (quote, spot price, execution setup, transfer proof, encsig) should have a blockchain network identifier, and messages on an incompatible network should be refused.