Mutli-chain accounts (Ethereum compatible)

[jasny]

Allow users to create secp256k1 accounts. See https://docs.ltonetwork.com/libraries/javascript/accounts#multi-chain-accounts

The users should (optionally) be able to choose a network for the derivation path (eg Ethereum). This will ensure that they'll get the same account when using the same seed in Metamask. Note that the derivation path doesn't matter for operating on either LTO Network or other chains.

[jasny]

Obtaining an Ownable that's bound to an NFT (most common use case) can only be done with a secp256k1 account.

💡 Maybe the user can switch between key types after being logged in. This way would work well with #76, when allowing the user to easily switch between accounts with the same seed but a different nonce.

[jasny]

Perhaps, choose the account type when creating an account.