ANDROID: rust_binder: add binderfs support to Rust binder

Add support for accessing the Rust binder driver via binderfs. The
actual binderfs implementation is done entirely in C, and the
`rust_binderfs.c` file is a modified version of `binderfs.c` that is
adjusted to call into the Rust binder driver rather than the C driver.

We have left the binderfs filesystem component in C. Rewriting it in
Rust would be a large amount of work and requires a lot of bindings to
the file system interfaces. Binderfs has not historically had the same
challenges with security and complexity, so rewriting Binderfs seems to
have lower value than the rest of Binder.

We also add code on the Rust side for binderfs to call into. Most of
this is left as stub implementation, with the exception of closing the
file descriptor and the BINDER_VERSION ioctl.

Link: https://lore.kernel.org/rust-for-linux/20231101-rust-binder-v1-2-08ba9197f637@google.com/


Change-Id: I18c03ae07b73f0fa9ef5569bba122b9791c667b0
Co-developed-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Bug: 278052745