[epic] web OpenAPI discoverability

[grokspawn]

operator-framework/catalogd#426 established rigor for the existing FBC web interface which provided the entire catalog FBC to a client, and #1570 intends to expand that web API to make the network traffic more efficient by providing the capability of limited-scope FBC query/response exchanges.

Catalogd exposes API endpoints in status.urls and currently only supports [base](https://github.com/operator-framework/catalogd/blob/main/docs/fetching-catalog-contents.md#fetching-clustercatalog-contents-from-the-catalogd-http-server
This epic is to focus on API discovery).

We would like to permit some kind of api discovery, similar to https://api.openshift.com/ or https://docs.docker.com/reference/api/hub/latest/ where one can programmatically interrogate the OpenAPI spec for the interface and exercise a selected API.