supply privacy info for image permission dialog

[brindy]

Reviewer: Mia
Asana: https://app.asana.com/0/414235014887631/470959007490761
CC: Cain

Description:

Simply add the privacy statement for adding images to the user's photo library.

Note that once the user grants or denies permission they will have to change this in Settings -> Privacy -> Photo Library. We should probably check for permission before showing the menu and hide "Save Image" if it is denied (or show some messaging to tell the user to update their permissions in settings) but that seems low priority for now.

Steps to test this PR:

Test 1

1. Navigate to an image
2. Long press the image and choose save
3. Note the privacy reason in the permission dialog and deny the request
4. Confirm the image is NOT in the photo library

Test 2

1. Reinstall the app (to clear any stored permissions)
2. Navigate to an image
3. Long press the image and choose save
4. Note the privacy reason in the permission dialog and accept the request
5. Confirm the image is in the photo library

Reviewer Checklist:

• Ensure the PR solves the problem
• Review every line of code
• Ensure the PR does no harm by testing the changes thoroughly
• Get help if you're uncomfortable with any of the above!
• Determine if there are any quick wins that improve the implementation

PR DRI Checklist:

• Get advice or leverage existing code
• Agree on technical approach with reviewer (if the changes are nuanced)
• Ensure that there is a testing strategy (and documented non-automated tests)
• Ensure there is a documented monitoring strategy (if necessary)
• Consider systems implications (Database connections, Grafana stats, CPU)

[subsymbolic]

Looks good!