feat(ocm): add WAYF configuration for reva OCM service

[MahdiBaghbani]

Although this PR is referenced under cs3org/OCM-STA#1, it is not directly part of the STA funded work. However, since the changes are closely related and beneficial to OCM, I decided to port them here as well for consistency.

This PR depends on this PR opencloud-eu/reva#393 to be merged in Reva.

Description

This PR adds "Where Are You From" configuration support for the Reva OCM service, enabling federation discovery functionality for Web application.

Technical

• OCM Configuration: Added two new configuration fields to ScienceMesh struct:

  • Federations: Path to JSON file for storing OCM federations data (default: {basepath}/federations.json)
  • InviteAcceptDialog: Frontend URL for landing when receiving an invitation (default: /open-cloud-mesh/accept-invite)

• Reva Integration: Updated OCM service configuration to pass WAYF related settings:

  • Added invite_accept_dialog to well-known OCM provider configuration
  • Added federations_file to ScienceMesh configuration

• Proxy Routes: Added two new unprotected endpoints for WAYF public access:

  • /sciencemesh/federations Federation listing endpoint
  • /sciencemesh/discover Federation discovery endpoint