Paging V3

[jamiesanson]

The paging implementation could (and should) be looked at again to make it more generic, enabling all pageable endpoints to work.

Proposed implementation

• FeedPager.kt becomes Pager.kt
• The inputs and outputs of FeedPager change to make it more generic, through the use of suspend callbacks
• FeedPager should now expose State and Event observable objects. State is non-transient, events are transient, but can be mapped into ViewState to make them non-transient.
• With this, more can be moved to the ViewModel. FeedController PagingController, and the input parameters to that determine how the screen presents.
• ViewModels are now emitted as opposed to models directly. This allows more genericism and self-contained logic

[jamiesanson]

Turns out this is a lot more work than initially thought. Because of this I'm backlogging this and moving to some quicker wins/adding more functionality.