We should standardise on <a download> rather than
<a download="download"> everywhere. The value of the download attribute
tells the browser what filename to use, but is overridden by the
Content-Disposition HTTP header. Since it’s not being used, we should
remove it for the sake of disambiguation.
When I split up the error messages on the check CSV page into multiple
templates, I also reduced the repetition of wrapping `<div>`s and macro
calls by moving them up outside the conditional blocks (see
8e947f315d).
Unfortunately I didn’t make the same adjustments for the one-off flow,
which meant that errors on these pages lost their styling. This commit
re-adds the styling for these error messages.
they're currently expecting a RecipientsCSV object - but we won't
always have that available if we're handling a single notification.
So make the partials take generic variables, and then use a jinja with
block to pass in the correct values from either the check csv page or
the check notification page.
Additionally set the notification check page to show errors nicely -
hide the send button if there were problems, and replace the header
rather than creating a job, after entering the placeholders, you now
send a single notification. This means we don't clog up s3 by creating
lots of one line CSV files.
