state: implement __copy__ and __deepcopy__ for MutableProxy

Allow state vars accessed through MutableProxy to be copied and unconnected
from the proxy. Copied objects that are modified will not mark the associated
field on the state as dirty.

Fix #1841
Fix REF-647

reflex/state.py

@@ -1313,3 +1313,22 @@ def __setattr__(self, name, value):
             super().__setattr__(name, value)
             return
         self._mark_dirty(super().__setattr__, args=(name, value))
+
+    def __copy__(self) -> Any:
+        """Return a copy of the proxy.
+
+        Returns:
+            A copy of the wrapped object, unconnected to the proxy.
+        """
+        return copy.copy(self.__wrapped__)
+
+    def __deepcopy__(self, memo=None) -> Any:
+        """Return a deepcopy of the proxy.
+
+        Args:
+            memo: The memo dict to use for the deepcopy.
+
+        Returns:
+            A deepcopy of the wrapped object, unconnected to the proxy.
+        """
+        return copy.deepcopy(self.__wrapped__, memo=memo)