Render OpenAPI documentation of endpoints, not just prepare its downloadable raw document version

[lsulak]

Feature Description

Currently the EventGate exposes /api endpoint that contains the whole OpenAPI documentation. But I would like this to be rendered via the browser directly, as it's pretty much common standard. This ticket addresses that.

Problem / Opportunity

It's not easy to know, for a human, what are the REST API endpoints that EventGate exposes.

Acceptance Criteria

Open API docs are rendered via GET /docs api endpoint