rust: drm: add driver abstractions

Implement the DRM driver abstractions.

The `Driver` trait provides the interface to the actual driver to fill
in the driver specific data, such as the `DriverInfo`, driver features
and IOCTLs.

Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Asahi Lina <lina@asahilina.net>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://lore.kernel.org/r/20250410235546.43736-4-dakr@kernel.org
[ MISC changes
    * remove unnecessary DRM features; make remaining ones crate private
    * add #[expect(unused)] to avoid warnings
    * add sealed trait
    * remove shmem::Object references
    * original source archive: https://archive.is/Pl9ys



  - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>