We strip most whitespace as of:
https://github.com/alphagov/notifications-admin/pull/1701
However we are still getting some bad email addresses through, for
example one that had a leading zero-width space character. This means
that the user sees a validation error; really we should just deal with
the mess for them.
So this commit also includes characters without Unicode character
property "WSpace=Y" (which includes zero-width space) to those which are
stripped from form submissions.
List taken from here: https://en.wikipedia.org/wiki/Whitespace_character
See issue and discussion here: https://bugs.python.org/issue13391
