Change first_name + last_name to display_name for User

[noahjade]

Description

Currently, the User has two fields: first_name and last_name. However, because we are using google authentication through firebase we only have access to the user's display name. This means we cannot reliably determine what a users first and last name is, as splitting by spaces could result in errors for people with spaces in their first name etc. As such currently both first_name and last_name are being populated with the display name.

User's name is currently only used on the dashboard welcoming message, so this isn't high priority. But if future features want to rely on this more this should be cleaned up.

Acceptance Criteria

• User should have a single name field instead of two

Implementation details

Both the user model and the end point will have to be updated. Any reference to first_name and last_name in the front end will also have to be updated, but there aren't many atm so it should be okay.

Testing notes

• Existing tests will have to be updated to reflect this change.