Add text field when selecting "no" for "Did you feel safe with this person's behavior?" during review

[jesseallhands]

We should give users the opportunity to anonymously provide additional details if they select "no" when answering the question "Did you feel safe with this person's behavior?" when leaving a review for a user, OR if their score using the slider scale is <0.25. This will:

1. Prevent false-positives where people accidentally select "no" (this currently happens on a regular basis) or accidentally don't move the slider.
2. Help support more easily and accurately identify problematic users.
3. Encourage users to provide more anonymous feedback (rather than "reporting", which seems extreme to some).

In either case, the following should happen after the user presses the button:

1. User should be taken to a new page with a free text box and text above the box that should read:

Please provide our safety team with details so we can keep Couchers safe for everyone. Anything you type below will be kept private. It will not be seen by [USERNAME] and will not be shown on the website. You will have a chance to leave a public reference on a different page.

2. The text field should be optional, and there should be a "back" button and a "continue" button at the bottom. Clicking continue submits the form and takes the user to the page where they can leave their public reference.

The text submitted via the form should be included in the notification sent to safety@couchers.org and stored on the backend. The notification should be similar to the current content/user "report" notification.

Components:

• [ ] Backend changes to enable appending the submitted text to the DB
• [ ] Backend changes to enable notification of support at safety@couchers.org (similar mechanic as reports currently work)
• [ ] Frontend changes to adjust current behavior
• [ ] Frontend changes to add new page with text field
• [ ] UI/UX Testing

[jesseallhands]

Related to #3443 and #4194