WT-9742 adds timestamp support to the tiered hook in the Python tests.  Timestamps are incorporated into the use of SimpleDataSet and ComplexDataSet - trying to do it more globally would have been substantial work, and doing it with the data sets gave us some pretty good coverage without a huge amount of effort.

keith.smith@mongodb.com raised some points in the PR that maybe we want to run these timestamp tests independently of the tiered hook.  In particular, run timestamped data set tests without tiering, and run tiered data set tests without timestamps.

The current implementation has some timestamp functionality partially separated out, and the tiered hook was enhanced in a couple ways to assist in the timestamp functionality.  It probably makes sense to rearrange this so there is an independent timestamp hook that can be run separately from or in conjunction with the tiered hook.  We'd need to make sure the hook infrastructure can handle multiple hooks (it should, but it has never been tested).  And in particular we should handle multiple hooks on the same function (again, should work, never tested).  Then we can get every combination we need.

To avoid long tests and redundant work, it would make sense for the timestamp hook to filter out any tests that don't import data sets (if this is possible), since timestamp testing only applies to data sets.