refacto: use structure default _id + aptic structure creation

src/admin/admin.controller.ts

src/admin/dto/pending-structure.dto.ts

src/structures/dto/structure.dto.ts

src/structures/schemas/aptic-structure.schema.ts

src/structures/schemas/structure.schema.ts

src/structures/services/aptic-structures.service.ts

src/structures/services/structures.service.ts

src/structures/structures.controller.ts

src/users/interfaces/user.interface.ts

src/users/schemas/user.schema.ts

src/users/users.service.ts