wip: add multisig cli

[tynes]

Work in progress pull request, still need to implement a few things

• finish implementing these methods

• getProposalMTX

• approveProposal

• rejectProposal

• sendProposal

• decide if multisig commands should be behind multisig flag, like admin commands

• add websocket event listeners for multisig specific events

[nodech]

Because we call this bmultisig-client there's no need to have them behind multisig commands.

[tynes]

Similar to the admin commands that follow admin, I was wondering if the multisig commands should follow multisig ie:

./bmultisig-cli multisig proposals

or

./bmultisig-cli proposals

Its a matter of UX and compatibility with bwallet-cli