Source value mapped more than once inspection for @ValueMapping

Nadie ha tomado este issue todavía.

For value mappings a source value can only be mapped once. For example
```
import org.mapstruct.Mapper;
import org.mapstruct.ValueMapping;

@Mapper
public interface ValueMapper {

enum A {
A,B
}

enum B {
A,B
}

@ValueMapping(source = "A", target = "B")
@ValueMapping(source = "A", target = "A")
A from(B b);
}
```
is invalide as source `A` is mapped twice. MapStruct report this as

> Source value mapping: "A" cannot be mapped more than once.

Currently the plugin does not recognize this as an error. An inspection should be added for this.

For normal mappings there is already an inspection implemented and could be used as an example: https://github.com/mapstruct/mapstruct-idea/blob/main/src/main/java/org/mapstruct/intellij/inspection/TargetPropertyMappedMoreThanOnceInspection.java.

Comienza con src/main/java/org/mapstruct/intellij/inspection/TargetPropertyMappedMoreThanOnceInspection.java, que proporciona el patrón de inspección existente. Sigue cómo detecta los mapeos normales duplicados y aplica el mismo enfoque a los valores de origen de @ValueMapping. Se considera terminado cuando los valores de origen duplicados se reconocen y se notifican con el mensaje de error esperado.

Escrito por el modelo de indexación a partir del texto del issue.