Make OffsetQueryPagingSource only work with Int

[veyndan]

Breaking API change! Maybe it's okay as we're releasing SQLDelight 2 soon…

Previously, we're just upcasting state.anchorPosition to a Long, which screws things up when we have between Int.MAX_VALUE and Long.MAX_VALUE items in our pager. This is because, when we refresh the paging source, getRefreshKey(state: PagingState) is called, and we'll end up with a very wrong state.anchorPosition, as it's no longer the "most recently accessed index in the list", but some truncated form of it. The result of getRefresKey(…) will end up being passed to load(params: LoadParams) in the form of params.key, and bad things will happen as it's not the value we're expecting.

The "fix" is just to force a maximum of Int.MAX_VALUE items instead of Long.MAX_VALUE. Room does the same thing in their implementation of this class.