Generate AES KeyPair lazily (#687)

* Generate AES KeyPair lazily

* Fix coverage

* Update post-review

* Fix pragma

* Make json dumps consistent between python and orjson

* Add comment

* Add comments re json parameter in HttpClient

kasa/json.py

@@ -11,5 +11,9 @@ try:
 except ImportError:
     import json
 
-    dumps = json.dumps
+    def dumps(obj, *, default=None):
+        """Dump JSON."""
+        # Separators specified for consistency with orjson
+        return json.dumps(obj, separators=(",", ":"))
+
     loads = json.loads