Orchestration: allow developers to send custom tx messages

[0xpatrickdev]

What is the Problem Being Solved?

As an orchestration developer, I want to send a message that isn't yet supported by the Orchestration API. I know executeEncodedTx exists, but I don't have access to via the CosmosOrchestrationAccount exo.

Description of the Design

Add an executeEncodedTx method to CosmosOrchestrationAccount that calls into IcaAccount.executeEncodedTx

Security Considerations

Message allowlists are controlled by the host chain, not the controller chain. If a developer attempts to send a message that isn't supported by a host they will receive an error. Exposing this shouldn't create security issues.

Scaling Considerations

This change will allow developers to extend the Orch API without needing changes in @agoric/orchestration for each new message type.

Test Plan

There is existing coverage of executeEncodedTx in bootstrap tests. A simple unit test for cosmos-orchestration-account should be sufficient here.

Upgrade Considerations

This change will be part of library code slated for an NPM orch release.