Adds jsonb field to va_notify_notfications

[MarchandMD]

Note: Delete the description statements, complete each step. None are optional, but can be justified as to why they cannot be completed as written. Provide known gaps to testing that may raise the risk of merging to production.

Summary

• This work is behind a feature toggle (flipper): YES/NO

yes

• (Summarize the changes that have been made to the platform)

This is the first step in the process to change the data-type of a field on va_notify_notifications table

Before this PR:

the metadata field was added as a string datatype to the aforementioned table.

After this PR:

A new callback_metadata field has been added as a jsonb datatype, and it will usurp the
existing metadata field, eventually.

• (If bug, how to reproduce)

N/A

• (What is the solution, why is this the solution?)

This is the solution because the use of jsonb is more idiomatic, and it follows the recommended best practice to adhere to strong migrations

• (Which team do you work for, does your team own the maintenance of this component?)

VA Notify

• (If introducing a flipper, what is the success criteria being targeted?)

N/A

Related issue(s)

1. https://github.com/orgs/department-of-veterans-affairs/projects/1415?pane=issue&itemId=87124754&issue=department-of-veterans-affairs%7Cvanotify-team%7C1422
2. https://github.com/orgs/department-of-veterans-affairs/projects/1415/views/1?pane=issue&itemId=85247150&issue=department-of-veterans-affairs%7Cvanotify-team%7C1411

• Link to ticket created in va.gov-team repo OR screenshot of Jira ticket if your team uses Jira
• Link to previous change of the code/bug (if applicable)
• Link to epic if not included in ticket

Testing done

• New code is covered by unit tests
• Describe what the old behavior was prior to the change
• Describe the steps required to verify your changes are working as expected. Exclusively stating 'Specs run' is NOT acceptable as appropriate testing

considering this PR is the first step along the strong-migration path to change a datatype, the step require to verify this change works as expected is to run the migration. The migration was run as part of this PR and it update the schema in-kind. Local run of the test suite for our module passed

• If this work is behind a flipper:
  • Tests need to be written for both the flipper on and flipper off scenarios. Docs.
  • What is the testing plan for rolling out the feature?

Screenshots

Note: Optional

What areas of the site does it impact?

(Describe what parts of the site are impacted andifcode touched other areas)

Acceptance criteria

• I fixed|updated|added unit tests and integration tests for each feature (if applicable).
• No error nor warning in the console.
• Events are being sent to the appropriate logging solution
• Documentation has been updated (link to documentation)
• No sensitive information (i.e. PII/credentials/internal URLs/etc.) is captured in logging, hardcoded, or specs
• Feature/bug has a monitor built into Datadog (if applicable)
• If app impacted requires authentication, did you login to a local build and verify all authenticated routes work as expected
• I added a screenshot of the developed feature

Requested Feedback

(OPTIONAL)What should the reviewers know in addition to the above. Is there anything specific you wish the reviewer to assist with. Do you have any concerns with this PR, why?