Support for non-interactive lazy minting with SDK

[bobwith2bees]

The SDK requires the mint requester to perform a SignTypedData request via their web3 wallet (i.e.Metamask.)

This is a feature request to have the SDK have an optional field where the minter can provide their own private key and have the SDK perform the signing request locally - without the need for an interactive pop up workflow.

Acceptance criteria:

• optional parameter - a list of private keys to be used for signing (I only need one, but there may be a multi-sig use case)
• optional parameter - a list of additional signatures for the mint request (other creators that have already signed by other means) to include in the mint call.
  --
  related - generate a typedSignedData request form - that can be used outside of the SDK to sign

[evgenynacu]

@bobwith2bees this can be done using SDK now
You can provide Ethereum based on the private key. Then it should work.

Pretty the same is done in SDK tests: when sdk is created, Ethereum instance is made from PK generated