[171] Migration to add is_confidential column to Reference table

[avinhurry]

Context

We occasionally receive requests from candidates to share references provided about them. However, the data controller is not obligated to comply with these requests.

To ensure clarity and adhere to best practices, we are updating our process to explicitly ask, at the time of collection, whether the reference can be shared with the candidate. This helps establish when a reference is provided in confidence.

This PR sets out the new column that will be used in the multistep form.

Changes proposed in this pull request

• Migration to add is_confidential column to Reference table. This does has a default value of true and is a boolean.
• Send to DfE analytics

Guidance to review

• Does the column name make sense to you?
• Does the column type make sense to you?
• Does not setting a default value make sense to you?

Things to check

• If the code removes any existing feature flags, a data migration has also been added to delete the entry from the database
• This code does not rely on migrations in the same Pull Request
• If this code includes a migration adding or changing columns, it also backfills existing records for consistency
• If this code adds a column to the DB, decide whether it needs to be in analytics yml file or analytics blocklist
• API release notes have been updated if necessary
• If it adds a significant user-facing change, is it documented in the CHANGELOG?
• Required environment variables have been updated added to the Azure KeyVault
• Inform data insights team due to database changes
• Make sure all information from the Trello card is in here
• Rebased main
• Cleaned commit history
• Tested by running locally
• Add PR link to Trello card

[avinhurry]

Add content to References journey to clarify confidentiality choice

[dcyoung-dev]

Small suggestion

[dcyoung-dev]

Naming is hard 😛