Ability/option to delete only the media from a message, not the rest of the message

[kasia-de]

Guidelines

• Yes, I have searched the existing requests

Feature Description

Part 1: Manually deleting media from a specific message.
Part 2: Adding a new option under "Data and storage" > "Manager storage" view that will only delete only media from older messages, not the messages themselves. And a separate duration to delete (text) messages.
Part 3: Per-chat media vs. full message deletion, as described in https://community.signalusers.org/t/disappearing-images-media/18617/3

Hello,

JW writes about Signal-JW, that they
"Added an option to delete ony media when deleting media from the All media screen."

I believe that it can be useful and valuable to permit the user to delete only the media associated with a message, while leaving the text, read reciepts, timestamp and so on in place. This should not impact security or privacy for the user of Molly or their contacts and communication.

Examples:

1. Someone sends a selfie, and says "how's my makeup?"
2. Someone sent you a package, so they send you an image of the tracking info, and a message "here's your tracking #"
3. You're messaging someone in a country that censors its citizens internet access, they send you a screenshot of failing connections, "these connections are blocked"

In all of these cases, you could later delete the image, while being able to review the chat and understand what you two were talking about.

The following information is no longer available to someone who obtains your unlocked Molly application:

1. what the person looked like in that picture. If there are no pictures of them in the chat, nor in their profile picture, then they may not be able to identify them in person.
2. anything about that package, where it was sent from, or the exact tracking info to look up later.
3. the connections that the person you were messaging, was making. Maybe the government confiscated your phone, and is hunting your contacts.

This should permit the user to keep less information, thus leaving less information at the disposal of whomever obtains your device.

Potential problems with this feature:
Part 1, 2, 3: whether it can be synced to other linked devices. I was assuming that this could not be syned across devices.
Part 1: whether this partial deletion request can be sent to the other members of the chat. In other words, whether you can delete just the media component from a message, and delete "delete for everyone" for your own messages.

[kasia-de]

Part 2 was partially implemented by JW in johanw666/Signal-Android@a7f171a.

I am suggesting to expand upon it to allow a separate timeline for deleting media and text, otherwise you could never delete the text, automatically, that is.