samples: rust: Provide example using the new Rust MiscDevice abstraction

This sample driver demonstrates the following basic operations:

* Register a Misc Device
* Create /dev/rust-misc-device
* Provide open call-back for the aforementioned character device
* Operate on the character device via a simple ioctl()
* Provide close call-back for the character device

Signed-off-by: Lee Jones <lee@kernel.org>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20241213134715.601415-3-lee@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>