chore: adapted IUser to our DB schema (#6627)

## About the changes
Our schema allows us to have null username or email. With this change at
least we'll get a compiler warning when using either of these properties

![Screenshot from 2024-03-20
12-20-45](https://github.com/Unleash/unleash/assets/455064/7e1b7846-43a4-4532-be39-5a7bbc14e9fc)

src/lib/types/user.ts

@@ -18,16 +18,16 @@ export interface UserData {
 
 export interface IUser {
     id: number;
-    name: string;
-    username: string;
-    email: string;
+    name?: string;
+    username?: string;
+    email?: string;
     inviteLink?: string;
     seenAt?: Date;
     createdAt?: Date;
     permissions: string[];
     loginAttempts?: number;
     isAPI: boolean;
-    imageUrl: string;
+    imageUrl?: string;
     accountType?: AccountType;
 }