Huge change that completely revamps the settings dialog and implements

per model settings as well as the ability to clone a model into a "character."
This also implements system prompts as well as quite a few bugfixes for
instance this fixes chatgpt.

gpt4all-chat/qml/MyDirectoryField.qml

@@ -11,7 +11,7 @@ TextField {
     color: text === "" || isValid ? theme.textColor : theme.textErrorColor
     background: Rectangle {
         implicitWidth: 150
-        color: theme.backgroundLighter
+        color: theme.backgroundDark
         radius: 10
     }
 }