API endpoint for listing read posts

[K4LCIFER]

Requirements

• [X] Is this a feature request? For questions or discussions use https://lemmy.ml/c/lemmy_support
• [X] Did you check to see if this issue already exists?
• [X] Is this only a feature request? Do not put multiple feature requests in one issue.
• [X] Is this a backend issue? Use the lemmy-ui repo for UI / frontend issues.
• [X] Do you agree to follow the rules in our Code of Conduct?

Is your proposal related to a problem?

Currently, if one only looks at a post and doesn't save it, it's difficult to locate that post in the future unless one has the title of the post to search, or specific keywords that can help find it.

Describe the solution you'd like.

A solution to this would be to record a history of posts that a user has interacted with. Interactions could be opening the post, opening an image, commenting, voting, etc.

Describe alternatives you've considered.

None.

Additional context

There may be some privacy issues associated with recording user activity history.

[Sjmarf]

The API provides a way to see a history of upvoted posts, though afaik lemmy-ui doesn't implement this. A history of which posts you've recently opened would be nice too.

[Nutomic]

We already store the posts that were marked as read by a user. To resolve this we need to add a new field GetPosts.read_only, similar to the existing fields saved_only or liked_only. Pretty simple to implement really.