ATest: GTest auto gen config support run_test_as in Android.bp .

Feature request from developer, support setting uid in Android.bp.

This relands I5604af5f20c45728d19f4c01396a20a74997f8a8 on top of
I2210c15b84f9b30e1cc23b426d463b34cf9ef94f.

Bug: 113359343

Test: source build/envsetup.sh ; lunch
    vim platform_testing/tests/example/native/Android.bp
    add
    test_options: {
        run_test_as: "1234",
    },
    in cc_test
    make hello_world_test
    cat out/target/product/xxxx/testcases/hello_world_test/hello_world_test.config
    Will see  <option name="run-test-as" value="1234" />
    below <test class="com.android.tradefed.testtype.GTest" >

Change-Id: I0b167c44c00ff0eab51443fc93dd8fa2abbe54cf