[api] Add 48-bit MAC address varint fast path for BLE advertisements (#15988)

tests/components/json/__init__.py

@@ -0,0 +1,9 @@
+from tests.testing_helpers import ComponentManifestOverride
+
+
+def override_manifest(manifest: ComponentManifestOverride) -> None:
+    # json's to_code calls cg.add_library("bblanchon/ArduinoJson", ...). C++
+    # unit test builds that pull json in transitively (e.g. api) need that
+    # library registration to happen, otherwise json_util.cpp fails to find
+    # ArduinoJson.h.
+    manifest.enable_codegen()