Let desktop and mobile clients know about web features

## Is your feature request related to a problem? Please describe.

ownCloud desktop and mobile apps have a limited feature set, but users could open the web UI for all the remaining features. For this, it would need capabilities or a new endpoint where clients could get information, which file actions are available for a resource (file/folder/space) in the web UI:

Related:
- https://github.com/owncloud/web/issues/7927
- https://github.com/owncloud/client/issues/10206

## Describe the solution you'd like

### 1) Add capabilities with the string `?details=$tabId` to extend the private link

Ugly, because clients would need to compose `http://host/owncloud/f/$fileId` + `?details=$tabId` manually

### 2) New endpoint that lets clients know all available file actions for a resource (file/folder/space)

Benefit would be, it could in the future also include a short-living token that allows certain actions in the web UI, without the need for re-login. (irrelevant with SSO)

## Describe alternatives you've considered

A while ago, I thought about using the AppProvider for this:
- https://github.com/owncloud/ocis/issues/2792

@tbsbdr @micbar @kulmann this would be a high-prio item right after oCIS GA.

/cc @TheOneRing