Add an initial version check for migration

[trivikram29]

new file:   src/dma/collector/sql/canonical/assessment-helper.sql
modified:   src/dma/collector/sql/canonical/assessment.sql
modified:   src/dma/collector/sql/sources/postgres/collection-queries.sql
modified:   src/dma/collector/workflows/readiness_check/_postgres.py
modified:   src/dma/collector/workflows/readiness_check/base.py

[google-cla[bot]]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[cofin]

@trivikram29 thanks again for the work on this. I've split some of your changes off into separate PRs since they impact the main collections scripts.

I've opened:

429

428

427

[cofin]

Merged in with #426