Support native hints on application class for native tests

[sdeleuze]

Currenlty broken in session-without-security sample with:

    ClassSource [className = 'com.example.demo.DemoApplicationTests', filePosition = null]
    => java.lang.IllegalArgumentException: Could not find class [org.springframework.nativex.hint.TypeHint]
       org.springframework.util.ClassUtils.resolveClassName(ClassUtils.java:334)
       org.springframework.core.type.classreading.MergedAnnotationReadingVisitor.visitAnnotation(MergedAnnotationReadingVisitor.java:116)
       org.springframework.core.type.classreading.MergedAnnotationReadingVisitor.access$000(MergedAnnotationReadingVisitor.java:43)
       org.springframework.core.type.classreading.MergedAnnotationReadingVisitor$ArrayVisitor.visitAnnotation(MergedAnnotationReadingVisitor.java:175)
       org.springframework.asm.ClassReader.readElementValue(ClassReader.java:3093)
       [...]
     Caused by: java.lang.ClassNotFoundException: org.springframework.nativex.hint.TypeHint
       java.lang.Class.forName(DynamicHub.java:1338)
       org.springframework.util.ClassUtils.forName(ClassUtils.java:284)
       org.springframework.util.ClassUtils.resolveClassName(ClassUtils.java:324)
       [...]