Improve handling of Statuses for Operations & Operators

[andrea-williams]

Describe the task

There's 2 goals to this ticket: (1) fix a bad-practice coding habit (that greatly increases the chance of errors); and (2) improve the readability of application status labels (e.g., not_registered -> Not Registered)

Acceptance Criteria

• remove all manual assignments of status in code with enums (e.g., we don't want to use operation.status = 'Pending' bc it's bad practice. Replace with operation.status = OperationStatus.PENDING)
• remove hacky string fixes to status strings in FE (such as calling capitalizeString() in Operations table)
• rework the Status labels in Django models. Sepehr's suggestion is to use

class Statuses(models.TextChoices):

        NOT_REGISTERED = "Not Registered"

        PENDING = "Pending"

        APPROVED = "Approved"

        REJECTED = "Rejected"

Additional context

• Add any other context about the task here.
• Or here

[andrea-williams]

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