add __repr__ to MagicsDisplay (#14378)

Here's more details on the `rich` side:

https://github.com/Textualize/rich/issues/3317

I don't see a good reason not to overload `__repr__` in this use case

.github/workflows/python-package.yml

@@ -34,7 +34,7 b' jobs:'
       run: |
         darker -r 60625f241f298b5039cb2debc365db38aa7bb522 --check --diff . || (
         echo "Changes need auto-formatting. Run:"
-        echo "    darker -r 60625f241f298b5039cb2debc365db38aa7bb522"
+        echo "    darker -r 60625f241f298b5039cb2debc365db38aa7bb522 ."
         echo "then commit and push changes to fix."
         exit 1
         )

IPython/core/magics/basic.py

@@ -40,6 +40,9 b' class MagicsDisplay(object):'
     def _repr_pretty_(self, p, cycle):
         p.text(self._lsmagic())
     
+    def __repr__(self):
+        return self.__str__()
+
     def __str__(self):
         return self._lsmagic()