Move validations done in the user controllers into DTO

[divinecharlotte]

Objective

Update user controller and move the validation logic to the DTO

Description

• Remove the organization type check redundancy in the user controller
• Add the validation in create-user.dto.ts
• Remove the organization name check redundancy in the user controller as its validation was done in create-user.dto.ts
• Use the function already created to check if an email is valid (IsEmail) and remove its check in the controller
• Remove variable redundancy based on the scopes they are being used

Acceptance

• The validations are moved into the DTO
• The application and the validation still work normally.
• All the test cases are passing.