Have set_embedded_elliptic_curve_key bind to a network

[kayabaNerve]

The issue with having a single key per embedded elliptic curve is that the Bitcoin processor (if compromised) leaks the decryption key for the Ethereum processor (as they're one in the same).

[kayabaNerve]

The issue also applies for the key used for the Subtrate DKG. The amount of keys being passed around is sufficiently annoying I'd argue we should have a single root key in the orchestrator, establish explicit derivation paths, and have the processor take its partially derived key (having it finish the derivation on its end so we only pass one key, not multiple).