Refactor configuration file parsing

Now the time for importing the kitty.config module has been halved, from
16ms from 32ms on my machine. Also, the new architecture will eventually
allow for auto generating a bunch of python-to-C boilerplate code.

kittens/tui/operations_stub.py

@@ -9,6 +9,6 @@ class CMD:
 
 def generate_stub() -> None:
     from kittens.tui.operations import as_type_stub
-    from kitty.conf.definition import save_type_stub
+    from kitty.conf.utils import save_type_stub
     text = as_type_stub()
     save_type_stub(text, __file__)