rust: Add stub support for rust_ffi modules

This adds stubs support for rust_ffi and rust_ffi_shared modules. Usage
should match current cc usage. The stubs generator leveraged is the cc
stubs generator.

Bug: 203478530
Test: m blueprint_tests
Change-Id: I043b9714a357cd5fe17c183ccdf86900f5172e0e
diff --git a/rust/testing.go b/rust/testing.go
index 0ce1b66..2082b52 100644
--- a/rust/testing.go
+++ b/rust/testing.go
@@ -80,7 +80,6 @@
 			no_libcrt: true,
 			nocrt: true,
 			system_shared_libs: [],
-			apex_available: ["//apex_available:platform", "//apex_available:anyapex"],
 			min_sdk_version: "29",
 			vendor_available: true,
 			host_supported: true,
@@ -88,6 +87,13 @@
 			llndk: {
 				symbol_file: "liblog.map.txt",
 			},
+			stubs: {
+				symbol_file: "liblog.map.txt",
+				versions: [
+					"29",
+					"30",
+				],
+			},
 		}
 		cc_library {
 			name: "libprotobuf-cpp-full",