Add union link connection type support (#5806)

* Add union type support

* Move code

* nit

comfy_execution/validation.py

@@ -0,0 +1,32 @@
+from __future__ import annotations
+
+
+def validate_node_input(
+    received_type: str, input_type: str, strict: bool = False
+) -> bool:
+    """
+    received_type and input_type are both strings of the form "T1,T2,...".
+
+    If strict is True, the input_type must contain the received_type.
+      For example, if received_type is "STRING" and input_type is "STRING,INT",
+      this will return True. But if received_type is "STRING,INT" and input_type is
+      "INT", this will return False.
+
+    If strict is False, the input_type must have overlap with the received_type.
+      For example, if received_type is "STRING,BOOLEAN" and input_type is "STRING,INT",
+      this will return True.
+    """
+    # If the types are exactly the same, we can return immediately
+    if received_type == input_type:
+        return True
+
+    # Split the type strings into sets for comparison
+    received_types = set(t.strip() for t in received_type.split(","))
+    input_types = set(t.strip() for t in input_type.split(","))
+
+    if strict:
+        # In strict mode, all received types must be in the input types
+        return received_types.issubset(input_types)
+    else:
+        # In non-strict mode, there must be at least one type in common
+        return len(received_types.intersection(input_types)) > 0