[TTAHUB-430] add approved and created date to activity report tables

[thewatermethod]

Description of change

• Added approvedAt as a database column. This is set to the most recent timestamp when the report status changed to approved. Otherwise it is null. Unlocking a report doesn't erase this column, but re-approving it afterwards does overwrite it.
• Added created date to the my alerts widget on the activity-reports page
• Added created date and approved date to the activity reports widget
• Added both fields to the CSV (the same function generates exports for both tables - if there isn't an approval date, it will be blank)

How to test

View the tables on /activity-reports and export CSVs. Check that the fields described above are displayed, and that everything else appears correct.

Issue(s)

• https://ocio-jira.acf.hhs.gov/browse/TTAHUB-430

Checklists

Every PR

• Meets issue criteria
• JIRA ticket status updated
• Code is meaningfully tested
• Meets accessibility standards (WCAG 2.1 Levels A, AA)
• [n/a] API Documentation updated
• [n/a] Boundary diagram updated
• [n/a] Logical Data Model updated
• [n/a] Architectural Decision Records written for major infrastructure decisions

Production Deploy

• Staging smoke test completed

After merge/deploy

• Update JIRA ticket status

[kryswisnaskas]

Looks good! 👍

Verified that the approvedAt date is updated in the database when the report is approved by all approvers.