Automatic info-page (metadata) for apps

### Description

When an app is deployed, it should expose a new page /info or /metadata that does not require authentication, and that is cached in memory.

This page should display information that is relevant for systems (SBS) that needs to use the app API.

- Documentation from service owner relevant for clients (SBS) (README.md or a special info file in repo)
- Swagger UI for APIs relevant for end user systems
- Metadata (app name, required security level, last updated, etc)
- Links to data models, auth policy (XACML), process (BPMN), Studio repo, etc

Future expansions of this page could be rendering of process, automatic generation of documentation for how to use the APIs based on process steps, strongly typed Swagger (based on data models).

### Why?
- Self-serve. Service owner can maintain the documentation for their apps. Simple link from service catalog in info.altinn.no, no need for stuff in altinndigital
- Important for the project and SBS that documentation is good, updated and easily available
- Solves https://github.com/Altinn/app-lib-dotnet/issues/692 in a better way

### Additional Information

_No response_