Increments the GraphicGroupId to a new,unused value that can be assigned to the next group.
Certain LEAD Leadtools.Annotations.Core.AnnObject are converted to two or more Leadtools.Dicom.DicomAnnotationObject, which are then "grouped" together. The DicomAnnotationsUtilities class maintains a GraphicGroupId that is used for each generated group. Once a GraphicGroupId is assigned to a group, it must no longer be used. The IncrementGraphicGroupId function is used to increment to the next unused value. The default behavior of this function is to add one to the previous GraphicGroupId, but this behavior can be changed by subscribing to the OnIncrementGraphicGroupId event, and changing the value of GraphicGroupId.
For an example, refer to FromAnnContainerToDataSet(dicomdataset,anncontainer).
