Helping survivors

Add a new presentation for people helping survivors of domestic violence.

Plus some other small fixes for the slideshow template.

This is needed to do tpo/community/l10n#40014 (closed) and tpo/community/l10n#40015 (closed)

To review the new slides: https://review.torproject.net/tpo/web/community/review-helping-su-zvcb0f/training/resources/helping-survivors/