Add test_*_enabled to enable/disable tests

tests/example.c

@@ -0,0 +1,20 @@
+#include "mgos.h"
+#include "tests_autogen.h"
+
+uint32_t test_example_period_ms = 10000;
+bool test_example_enabled = true;
+
+bool test_example_create(void) {
+  // LOG(LL_INFO, ("Setting up"));
+  return true;
+}
+
+bool test_example_run(void) {
+  // LOG(LL_INFO, ("Hello World!"));
+  return true;
+}
+
+bool test_example_destroy(void) {
+  // LOG(LL_INFO, ("Tearing down"));
+  return true;
+}