BREAKING CHANGE: Apply database migrations to reduce complexity

[cmenon12]

Description

Create migrations to apply breaking changes to reduce the application complexity:

• Migration statuses are stored in the migrations collection.
• Rollback is not supported.
• A relevant section has been added to the README.

The five migration scripts are:

• Add next question value - if a prototype question is not branching and doesn't have a next_question_value, then add this as pointing to the next question, or to finish if it's the last question.
  • This allows us to assert that branching questions will never have a next_question_value, and non-branching questions always will.
• Add show progress indicators - if a prototypes doesn't have show_progress_indicators, add it as true if the prototype doesn't contain a branching question, otherwise false.
  • This allows us to assert that this property is always present.
• Add isActive and isAdmin booleans to users - add these if not defined, and ensure at least one user is an admin.
  • This will be used by Create an admin user panel to manage users #128 and Create an admin user screen, allow users to be deactivated #130.
  • Also ensure that the first user to register is created as an admin user.
• Add prompt and remove chat history - add a prompt property to all prototypes created from a text prompt (create or update) or set as undefined if created from JSON. Delete the chat history.
  • This allows us to assert that prototypes created from a text prompt will always have a prompt property, and those created from JSON never will.
  • This follows on from Remove all references to chatHistory, add a prompt property instead #86.
• Remove the timestamp property from prototypes.
  • This allows us to use the MongoDB createdAt property instead.

Also:

• Fix the type used for createdAt and updatedAt properties.

A new release will need to be created as a major update, with clear instructions to run the migrations.

Related issues: closes #85

Checklist before marking as ready for review

Before marking as ready for review, please check that you have:

• Added appropriate and passing tests for the changes I made.
• Not broken any existing functionality or tests.
• Not introduced any new linting or formatting errors.
• Only added new dependencies that are necessary, do not introduce security vulnerabilities, and with tilde (~) version ranges.
• Checked and resolved UI accessibility issues using Axe devtools. Unresolved issues are described above.
• Updated the documentation if necessary.

Check the contributing guidelines for more details.

Screenshots (if appropriate)