feat(interfaces): add IReqRegister interface

This interface defines the register request structure, including `username`, `displayName`, `firstName`, `lastName`, `password`, and `gdpr` status. This will ensure consistency in the form of request data throughout the application.

Signed-off-by: Mathis <yidhra@tuta.io>

src/interfaces/requests/IReqRegister.ts

@@ -0,0 +1,8 @@
+export interface IReqRegister {
+	username: string;
+	displayName: string;
+	firstName: string;
+	lastName: string;
+	password: string;
+	gdpr?: boolean;
+}