Registry: Add wait-for-deps and basic db-migrate

What does this MR do?

Add two scripts to gitlab-container-registry:

1. wait-for-deps: shell based, and including a method checking the output of migrate status table. Includes BYPASS_SCHEMA_VERSION behaviors.
2. db-migrate: simple, without cursory checks on status (or retry). Should be used with BYPASS_SCHEMA_VERSION=1 /scripts/wait-for-deps /scripts/db-migrate

Related issues

Relates to https://gitlab.com/gitlab-org/charts/gitlab/-/issues/2565

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion

Required

• Merge Request Title, and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Integration tests added to GitLab QA
• The impact any change in container size has should be evaluated