Python view text editor now uses a fixed-width font

One can no longer paste text with rich text formatting into the
editor. This should help avoid potential readability problems
caused by not being able to remove formatting.

Change-Id: I038dc802d15120912e8f929953931399c7fd328f
Merge topic '14501-python-view-fixed-width-editor' into next

3100282 Python view text editor now uses a fixed-width font