#13997 3dView: Show active filter name(s) below Z-scale indicator

Adds a new HUD label in the upper-left of the 3D view that reads
"Filter : <name(s)>" whenever a cell, property, or per-view data
filter is active. The label is hidden when nothing is enabled.

Names are joined per the source collection's AND/OR combine mode, and
contributions from different collections are concatenated with ", ".
On Eclipse views the unified RimFilterInViewCollection is used as the
single anchor; GeoMech views aggregate cell and GeoMech property
filters directly.

ApplicationLibCode/UserInterface/RiuViewer.h

@@ -89,6 +89,9 @@ public:
     void showZScaleLabel( bool enable );
     void setZScale( double scale );
 
+    void showFilterLabel( bool enable );
+    void setFilterText( const QString& text );
+
     void showHistogram( bool enable );
     void setHistogram( double min, double max, const std::vector<size_t>& histogram );
     void setHistogramPercentiles( double pmin, double pmax, double mean );
@@ -179,6 +182,9 @@ private:
     double  m_zScale;
     int     m_fontSize;
 
+    QLabel* m_filterLabel;
+    bool    m_showFilterLabel;
+
     caf::QStyledProgressBar*  m_animationProgress;
     caf::QStyledProgressBar*  m_animationProgressCompView;
     bool                      m_showAnimProgress;