Add Rust fuzzing support.

Add a rust_fuzz module which builds a libfuzzer binary that enabes
asan+sancov. This relies on the libfuzzer-sys crate.

Bug: 147140513
Test: Local rust_fuzz example builds, fuzzes with asan+sancov.
Change-Id: I57db3b8d25869791824ccfab768d13b0bb9d42fa

rust/Android.bp

@@ -15,6 +15,7 @@ bootstrap_go_package {
         "clippy.go",
         "compiler.go",
         "coverage.go",
+        "fuzz.go",
         "image.go",
         "library.go",
         "prebuilt.go",
@@ -22,6 +23,7 @@ bootstrap_go_package {
         "project_json.go",
         "protobuf.go",
         "rust.go",
+        "sanitize.go",
         "strip.go",
         "source_provider.go",
         "test.go",
@@ -34,6 +36,7 @@ bootstrap_go_package {
         "clippy_test.go",
         "compiler_test.go",
         "coverage_test.go",
+        "fuzz_test.go",
         "image_test.go",
         "library_test.go",
         "project_json_test.go",