[Replay Details] Improve useReplayData so that it returns attachments in-order

[ryan953]

Currently in useReplayData() we have a helper [fetchAttachments() https://github.com/getsentry/sentry/blob/272db4d46dad6370ac1b0d19a96f63cd7197f1f0/static/app/utils/replays/hooks/useReplayData.tsx#L125](https://github.com/getsentry/sentry/blob/272db4d46dad6370ac1b0d19a96f63cd7197f1f0/static/app/utils/replays/hooks/useReplayData.tsx#L125-L157)

This takes a list of generated cursors and, instead of paging through data, fetches everything in parallel. This is better for loading things quickly, but the data can arrive out of order. Therefore it will be concatenated into setAttachments() out of order too.

We should track order so that when we return the attachment list everything is returned in order.

If the data is returned in-order here, then we can remove extra sorting inside of ReplayReader. The RRWeb player component needs rrweb data returned in order, but we can trade cpu/memory during load with some more js code.