DANS Optimizations of UpdateDatasetVersionCommand

[qqmyers]

What this PR does / why we need it: Work in progress to test ways to speed editing of datasets with many (10K+) files. With updates to the DatasetVersionDifference and changes to avoid merging (more than once) the version being edited, this is currently 5-10x faster for metadata edits.

The draft PR is primarily to share the work with DANs and to make sure the changes aren't breaking tests/IT tests.

Which issue(s) this PR closes:

Closes #

Special notes for your reviewer:

Suggestions on how to test this:

Does this PR introduce a user interface change? If mockups are available, please link/include them here:

Is there a release notes update needed for this change?:

Additional documentation:

[coveralls]

coverage: 22.535% (-0.04%) from 22.571% when pulling 1dda2e6504dd72ceee152525443d33fd98f5b4a9 on GlobalDataverseCommunityConsortium:DANS-remove_async_dates_from_main_tables into a4d01270da53e1d76420c3f607a699f05e59fa8c on IQSS:develop.