Add Icon to roles (#10842)

## Context
Adding icon column to role table to distinguish roles.

<img width="621" alt="Screenshot 2025-03-13 at 11 02 37"
src="https://github.com/user-attachments/assets/dc7b121c-2901-4599-9638-d5dcdf443999"
/>

packages/twenty-server/src/engine/metadata-modules/role/dtos/role.dto.ts

@@ -16,6 +16,9 @@ export class RoleDTO {
   @Field({ nullable: true })
   description: string;
 
+  @Field({ nullable: true })
+  icon: string;
+
   @Field({ nullable: false })
   isEditable: boolean;