accounts: Normalize roll number to ensure uniformity

[shiveshcodes]

Is your feature request related to a problem? Please describe.
Roll numbers for students in batches since '22 now include a single letter (<B or M or N or ...><Dept + Student>).
Since these can be written as both lowercase and uppercase characters, this causes a possible duplication in user fields

Describe the solution you'd like
Implement a normalization method on the roll number field on the backend, that ensures that the roll number is always *UPPERCASE. This is not by requirement, but a convention that is suggested.

Describe alternatives you've considered
While this could also be implemented on the frontend, it would have to be implemented over multiple pages and components, while doing so on the back-end would only require adding at most two functions to the User model.

Additional context
N.A