Multisig AID participation and management API requests

[2byrds]

Task List:

• Multisig AID Inception request - initialization
• Multisig AID Inception request - join
• Multisig AID Rotation request
• Multisig AID Interaction request
• Delete AID request

[2byrds]

Depends on WebOfTrust/keria#18

[kentbull]

Delete AID will be moved to a separate PR. Everything else here has been accomplished.