Context coordinator joining ceremony

[fbozic]

At the moment, the user must run meroctl context join command against the coordinator node. Implement coordinator joining ceremony for the context. Part of the context creation process should include an automated coordinator joining process.

Rough idea:

• The context creator should broadcast a request for coordination to a dedicated topic.
• All (interested) coordinators should reply with a coordination offer.
• A context creator picks the most suitable offer and broadcasts the offer acceptance.
• The coordinator whose offer is accepted should join the context topic.
• Consider storing the chosen coordinator for context and validating transaction confirmation/rejection.

Subtasks

• [x] https://github.com/calimero-network/core/issues/582
• [x] https://github.com/calimero-network/core/issues/583
• [x] https://github.com/calimero-network/core/issues/584

[fbozic]

Initial estimation: ~2 weeks

[MatejVukosav]

Deprecating in favour of a new synchronization mechanism using CRDT