[android] Implement android test runner for core unit tests

platform/android/src/test/test_runner.cpp

@@ -0,0 +1,10 @@
+#include "runtime.hpp"
+#include <mbgl/test.hpp>
+
+int main(int argc, char *argv[]) {
+    if (!mbgl::android::initRuntime(argc, argv)) {
+        return 1;
+    }
+
+    mbgl::runTests(argc, argv);
+}