quote the filename in the default editor hook - #15364

The default editor hook runs the editor through the shell without quoting the filename:

• editor() in core/hooks.py builds the command with shell=True and interpolates the filename raw
• %edit only wraps the path in quotes when it has a space, so a filename with ';', '$(...)' or backticks runs before the editor opens
• the path is not always user-typed: %edit on an object resolves it from the object's source file via inspect.getabsfile

install_editor already shlex-quotes the filename inside the hook; this makes the default hook do the same and drops the now-redundant quoting in %edit.