Add support for collection enumeration to the remote store protocol

[drauschenbach]

What

The remote store protocol is being extended to support enumeration of collections.

This PR also aims to prototype a more scalable organization of proto files:

• A catalog model is centrally defined for reuse by related request and response messages
• When a catalog model is provided in a request, it is repeated in the response, providing access to its finalized field values such as an assigned id or created at timestamp

[github-actions]

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Result	Commit	Link	Manifest
✅	c5cfb5d	https://rerun.io/viewer/pr/9121	+nightly +main

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