Add an option to get all versions of rows in the /diff API

[wbrunette]

@kervel has posted a pull request for this improvement

Pull Request: odk-x/sync-endpoint#31

"By default, the /diff API only returns the latest version of a row in one fetch block. When the full history is needed, now one can pass getFullLog=true to get ALL changes

see https://forum.opendatakit.org/t/retrieving-the-full-history-of-an-odk-x-table-from-the-server/21314 for more context"

[wbrunette]

From @kervel
"Hello @wbrunette

Thanks for the feedback. I'm trying to give some extra context that might be relevant to the discussion on the TSC:

• our usecase is a migration tool (which we plan to release as part of odkxpy) that - i think - should be quite useful for other people outside our team: think of migrating to a new server, disaster recovery, or transferring to a new version of the form with some schema changes (so it will be possible to specify column mappings as part of a migration)

• i don't really think this change exposes more information than it already did: if you set the batchSize to 1, you will get exactly the same (albeit extremely slow, having to retrieve row by row), since the version deduplication is only done per batch (and not globally).

If needed, we can join the relevant meeting and explain our goals further.

Frank"