Spring Security Implement OAuth 2.0 Protected Resource Metadata

Add support for OAuth 2.0 Protected Resource Metadata.

See the following integration test on how to customize the metadata response:

https://github.com/spring-projects/spring-security/blob/54aae36f9871e44adf817c1e4da61388d175a735/config/src/test/java/org/springframework/security/config/annotation/web/configurers/oauth2/server/resource/OAuth2ProtectedResourceMetadataTests.java#L113

Comment From: jochenchrist

This feature is required for MCP Server OAuth authentication: https://modelcontextprotocol.io/specification/2025-06-18/basic/authorization#authorization-server-location