rust: Add export_include_dirs property to rust_ffi

The cc property include_dirs is neverallowed in certain paths since it
has been deprecated. The property in rust_ffi modules with the same name  functionally works the same way as the CC property export_include_dirs.

To reduce confusion, and avoid triggering the neverallow rule, deprecate
include_dirs and create an export_include_dirs property which does the
same thing. This brings rust module properties into better alignment
with cc module property as well, reducing confusion.

Bug: 330736943
Test: New Soong test
Change-Id: Ib2020a22e6747ac690c46dbff84e38744f93ed15

rust/library_test.go

@@ -403,3 +403,22 @@ func TestLibstdLinkage(t *testing.T) {
 	}
 
 }
+
+func TestRustFFIExportedIncludes(t *testing.T) {
+	ctx := testRust(t, `
+		rust_ffi {
+			name: "libbar",
+			srcs: ["foo.rs"],
+			crate_name: "bar",
+			export_include_dirs: ["rust_includes"],
+			host_supported: true,
+		}
+		cc_library_static {
+			name: "libfoo",
+			srcs: ["foo.cpp"],
+			shared_libs: ["libbar"],
+			host_supported: true,
+		}`)
+	libfooStatic := ctx.ModuleForTests("libfoo", "linux_glibc_x86_64_static").Rule("cc")
+	android.AssertStringDoesContain(t, "cFlags for lib module", libfooStatic.Args["cFlags"], " -Irust_includes ")
+}