Expand user directory for basepath in extra_models_paths.yaml (#4857)

* Expand user path.

* Add test.

* Add unit test for expanding base path.

* Simplify unit test.

* Remove comment.

* Remove comment.

* Checkpoints.

* Refactor.

utils/extra_config.py

@@ -0,0 +1,25 @@
+import os
+import yaml
+import folder_paths
+import logging
+
+def load_extra_path_config(yaml_path):
+    with open(yaml_path, 'r') as stream:
+        config = yaml.safe_load(stream)
+    for c in config:
+        conf = config[c]
+        if conf is None:
+            continue
+        base_path = None
+        if "base_path" in conf:
+            base_path = conf.pop("base_path")
+            base_path = os.path.expanduser(base_path)
+        for x in conf:
+            for y in conf[x].split("\n"):
+                if len(y) == 0:
+                    continue
+                full_path = y
+                if base_path is not None:
+                    full_path = os.path.join(base_path, full_path)
+                logging.info("Adding extra search path {} {}".format(x, full_path))
+                folder_paths.add_model_folder_path(x, full_path)