Deprecate PdfRichMediaAnnotation class

DEVSIX-3400

Author: EvgenyB1001

kernel/src/main/java/com/itextpdf/kernel/pdf/annot/PdfRichMediaAnnotation.java

@@ -47,6 +47,11 @@ This file is part of the iText (R) project.
 import com.itextpdf.kernel.pdf.PdfDictionary;
 import com.itextpdf.kernel.pdf.PdfName;
 
+/**
+ * @deprecated Remove this class in 7.2. The deprecation relates to the fact that the prototype
+ * hasn't been implemented in a full yet and we do not expect the situation to change.
+ */
+@Deprecated
 public class PdfRichMediaAnnotation extends PdfAnnotation {
 
     private static final long serialVersionUID = 5368329326723025646L;