fix: add pagination to list tx

[rukmini-basu-da]

This PR updates the listTransactions user-api and store interface to accept an optional parameter that consists of {limit: number, cursor: string}).

The sql store and in memory implementations where both updated to query the same way with createdAt desc nulls last, using the id desc as the tiebreaker. The reason why the transactions table createdAt column is nullable (rather than something like currentTimestamp if not provided) is this was implemented for an audit trail and currentTimestamp is not necessarily accurate (hence the additional paging logic). The store requests pageSize+1 items, so if an additional item is returned, we know there is a next page (and this element is removed before returning the payload and also determines the nextCursor).

Lastly, the user-ui-activities in the remote wallet-gateway used to listTransactions and get all the elements then implement pagination on the client side, so this was modified to use this.transactions as a paginated stream provided by the server. The pageCursors is sequentially cached where page 1 maps to undefined and as it's navigated forward, the nextCursor is sequentially cached, which helps with backwards/forwards traversal of the transactions pages.

[alexmatson-da]

thx!