[BUG] Rich.pretty breaks IPython built-in %pprint

[aroberge]

Describe the bug
When using rich.pretty, the builtin %pprint command results in a traceback

%pprint is intended to toggle on and off the pretty printing, something which is not supported by Rich in general.

To Reproduce

In [1]: from rich import pretty

In [2]: pretty.install()

In [3]: %pprint
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)

... (lines removed)
    306         """Toggle pretty printing on/off."""
    307         ptformatter = self.shell.display_formatter.formatters['text/plain']
--> 308         ptformatter.pprint = bool(1 - ptformatter.pprint)
    309         print('Pretty printing has been turned',
    310               ['OFF','ON'][ptformatter.pprint])

AttributeError: 'BaseFormatter' object has no attribute 'pprint'

Possible solutions

• Ideal solution: rich.pretty supports %pprint
• Next best solution: Attempting to use %pprint with rich.pretty results in a message indicating that this is not supported
• Minimal solution: A note is added in the documentation about this feature not being supported and a message is printed
  when pretty is installed inside IPython.

Platform
Windows 10; Windows Terminal

Diagnose
rich==10.12.0
ipython==7.25.0

[aroberge]

I believe that adding the following would work as a minimal implementation:

from IPython.core.magic import register_line_cell_magic
@register_line_cell_magic
def pprint(_line=None, _cell=None):
    print("%pprint is not supported by Rich.")

[aroberge]

Closing as this was taken care of in #1646

[github-actions]

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