Make a trait out of PaginationCursor / PaginationCursorData

[dessalines]

Requirements

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Is your proposal related to a problem?

We currently have a lot of custom PaginationCursors (PostView, all the new Combined endpoints that now use pagination cursors) , with the same after_post and read functions.

Describe the solution you'd like.

This should be made into a trait that each one can implement.

Also, see this comment about making a helper function for ids / prefixes

Describe alternatives you've considered.

NA

Additional context

NA

[dessalines]

I'll take a look at doing this as part of the 1.0.0 milestone. If it doesn't work out I'll just close this.