[MultiSig] Implement 2 steps (resolveMultisigIndices -> sign)

[peak3d]

Multisig / SigIndices

This PR changes the logic from automatically traversing through msig aliases on sign() in favour of a 2 step logic

Workflow of creating a MultiSig TX

• buildUnsignedTx with providing MultiSigAlias in "from"
• resolveMultisigAlias with the MultisigAliasSet class which:
  -- flattens the multisig alias /which could be nested from theory) into a single array of addresses
  -- if no addresses are provided, wildcard sigIndices are generated
  -- replaces the sigIndices for all inputs / auths to the new flattened list
• create a MultiSigKeychain with all signatures and sign the transaction
• issue TX

Caveats

In case no addresses are provided in resolveMultisigAlias step (signavault mode), the sigIndices all countain a magic number and no sourceAddress (because it was not known beforehand who signs)
To finally create the correct signatures, the original base outputowners off all input UTXOs have to be either saved or pulled from node using UTXOId to be able to re-run the resolve step and build the signatures in right order.
This is not yet implemented

[DerTiedemann]

LGTM