feat: add custom node class

diagrams/custom/__init__.py

@@ -0,0 +1,20 @@
+"""
+Custom provides the possibility of load an image to be presented as a node.
+"""
+
+from diagrams import Node
+
+
+class Custom(Node):
+    _provider = "custom"
+    _type = "custom"
+    _icon_dir = None
+
+    fontcolor = "#ffffff"
+
+    def _load_icon(self):
+        return self._icon
+
+    def __init__(self, label, icon_path):
+        self._icon = icon_path
+        super().__init__(label)