Changed the way read posts are handled to support an arbitrary read posts limit

[blahberi]

Context

Currently, read posts are loaded from the room database to memory in a List<ReadPost> during usage. The list is used to mark posts being loaded as read during post parsing. Due to performance reasons (saving the state of the list), the read posts database is limited to 500 entries.

Changes

Change how we handle read posts when new posts are loaded.

We can instead mark loaded posts as read directly from the db.

• Instead of using a List<ReadPost> to handle read posts, we use ReadPostsListInterface, which contains the necessary methods for marking loaded posts as read.
• The implementation of ReadPostsListInterface (called ReadPostsList) just uses ReadPostDao.
• We change parsePostSync() to work with the new ReadPostsListInterface instead.

Since read posts are not loaded to memory anymore, we can now set an arbitrary read posts limit.

Add a setting to customize the read post limit

• A switch that lets you choose whether you even want a read post limit
• An input for setting a custom read post limit (default is 500, minimum is 100)
• A summary of the read post db in "Advanced" preferences, so you can monitor its size.

[Docile-Alligator]

Thank you very much!