move all models into subdirectories of ./models

- this required an update to the invoke-ai fork of gfpgan
- simultaneously reverted consolidation of environment and
  requirements files, as their presence in a directory
  triggered setup.py to try to install a sub-package.

ldm/invoke/args.py

@@ -500,13 +500,13 @@ class Args(object):
         postprocessing_group.add_argument(
             '--gfpgan_model_path',
             type=str,
-            default='experiments/pretrained_models/GFPGANv1.4.pth',
+            default='./GFPGANv1.4.pth',
             help='Indicates the path to the GFPGAN model, relative to --gfpgan_dir.',
         )
         postprocessing_group.add_argument(
             '--gfpgan_dir',
             type=str,
-            default='./src/gfpgan',
+            default='./models/gfpgan',
             help='Indicates the directory containing the GFPGAN code.',
         )
         web_server_group.add_argument(