feat(core): api based registration to speed up initial agent discovery

[ejfitzgerald]

TBD

Proposed Changes

[describe the changes here...]

Linked Issues

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Types of changes

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• [ ] Bug fix (non-breaking change that fixes an issue).
• [ ] New feature added (non-breaking change that adds functionality).
• [ ] Breaking change (fix or feature that would cause existing functionality to stop working as expected).
• [ ] Documentation update.
• [ ] Something else (e.g., tests, scripts, example, deployment, infrastructure).

Checklist

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• [ ] I have read the CONTRIBUTING guide
• [ ] Checks and tests pass locally

If applicable

• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] I have checked that code coverage does not decrease
• [ ] I have added/updated the documentation

Further comments

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[Alejandro-Morales]

This PR was split into two parts, 1st part introduces data types (can be merged immediately), while the second one introduces registration changes (can be merged until almanac-api changes are released to prod)

1. https://github.com/fetchai/uAgents/pull/457
2. https://github.com/fetchai/uAgents/pull/458