make undecorated windows place according to their undecorated state (bug #5179)

splits client_setup_decor_and_functions() into 3 functions.

1. add client_setup_default_decor_and_functions()
- called from client_get_all() to get the maximum decor/functions that will
  be available for use by the client.
2. add client_setup_decor_undecorated()
- sets up the client's undecorarted decor if the flag is set by the per-app
  settings or session state.
- we do this before setting up the frame so the frame reflects the window as it
  should be when getting placed.
3. client_setup_decor_and_functions()
- calls the above 2 to perform the same functions as before.
- added to client_apply_startup_state() so that we can ensure it was run fully
  at least once in the mapping process, since it is not called in
  client_get_all() anymore.