rust: add PL011 device model

rust: add PL011 device model

This commit adds a re-implementation of hw/char/pl011.c in Rust.

How to build:

1. Configure a QEMU build with:
   --enable-system --target-list=aarch64-softmmu --enable-rust
2. Launching a VM with qemu-system-aarch64 should use the Rust version
   of the pl011 device

Co-authored-by: Junjie Mao <junjie.mao@intel.com>
Co-authored-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Junjie Mao <junjie.mao@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Link: https://lore.kernel.org/r/6ec1d4fb8db2a1d7ba94c73e65d9770371b7857d.1727961605.git.manos.pitsidianakis@linaro.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>