Integrate vkjson tests into Presubmit

* Moved existing unit tests into a test subfolder
* Moved existing testing infra (such as BaseCodeAssertTest) into a separate file within the test subfolder
* Hooked the tests into presubmit test suite through Android.bp files

Bug: b/416165162
Flag: NONE infeasible
Test: atest native_vulkan_scripts_test
Change-Id: Id5bb4c88f0930aba01904149313ad6db928c9d78