update opened_at to be nullable

[maryhipp]

Summary

Update schema for WorkflowLibrary to allow nullable opened_at to better represent when a workflow has never been opened. Opted to make a new column versus repurposing old one, which means users will lost historical "opened_at" data but will have better data integrity going forward.

Related Issues / Discussions

QA Instructions

Merge Plan

Checklist

• The PR has a short but descriptive title, suitable for a changelog
• Tests added / updated (if applicable)
• Documentation added / updated (if applicable)
• Updated What's New copy (if doing a release after this PR)

[psychedelicious]

There is no real historical data, it's fake news. Was never actually used by OSS UI. I will update the migration to simply wipe the column.

[psychedelicious]

• Fix conflicts from feat: workflow library iteration 2 #7765
• Fix some perf issues
• Ensure index is recreated for new column, drop the old column entirely bc there's no valuable data in it
• Rename is_recent -> has_been_opened
• Rework how we store the selected view for library. Previously we were deriving the view from selected categories and whether or not we are showing workflows that have been opened. Basically storing the query args and deriving the view from that, which is confusing and tedious. Reversed it so that now we store view: 'recent' | 'yours' | 'private' | 'shared' | 'defaults' in state, and derived the query args from the view.
• Added method to get counts for individual categories so that we can. This allows us to check if the user's selected view has no workflows to show, and switch to the next available view that has workflows to show. For example, if the user has no recent workflows or user workflows, we should show the default workflows initially. If the user has no recents, but does have user workflows, we should instead show the user's workflows initially.
• When creating a new workflow, mark it as opened at the time it was created so it shows up in recents