Add rust binaries to link with C++ staticlib

Rather than using C++ binaries to link with Rust staticlib, we do it the
other way around. This allows us to write our dbus frontend with Rust
instead.

Bug: 179821440
Tag: #floss
Test: atest --host bluetooth_test_gd
Change-Id: I63037e0aaea152a4855e0a49971c1b2f9c312ac5