Install rust tests under nativetest(64)

* Now the installation directories match those for C/C++ tests:
  * The relative_install_path refers to path under nativetest(64).
  * Device test files are installed in data/nativetest(64).
  * Automatically generated configuration files and copied test binaries
    are still in the "testcases" directory.
* Change host test configuration to run test binary files
  in testcases/<mutated_module_name>/<arch_type>/<stem_name>

Bug: 140938178
Test: atest --include-subdirs under external/rust/crates
Change-Id: I4b29afb897f4ba8749e87f79857c5b1a959bb2b0