Additional API endpoints: Delete cache on registry and upstream

To achieve parity with the API endpoints that Maven offers, there are additional endpoints that we need to add.This issue focuses on the endpoints to clear the cache on a registry and an upstream. We aim to add the following endpoints:

Route	Notes
DELETE /virtual_registries/container/registries/:id/cache	Clear cache on a registry
DELETE /virtual_registries/container/upstreams/:id/cache	Clear cache on an upstream

References:

• https://docs.gitlab.com/api/maven_virtual_registries/#delete-cache-entries-for-a-virtual-registry
• https://docs.gitlab.com/api/maven_virtual_registries/#delete-cache-entries-for-an-upstream-registry

After the endpoints are added, update the API documentation.