#12790 Replaces transparency with opacity settings

Simplifies color handling by replacing transparency settings with opacity for curve and fill colors.

This change provides a more intuitive user experience and ensures consistent behavior across the application.

- Renames "ColorTransparency" to "ColorOpacity" for RimCurveSetAppearance.
- Introduces "CurveColorOpacity" for RimPlotCurveAppearance.
- Updates blending calculations to correctly use opacity.
- Adjusts UI slider attributes for opacity settings, including minimum, maximum and decimals.

ApplicationLibCode/ProjectDataModel/Histogram/RimHistogramCurve.cpp

@@ -477,6 +477,6 @@ void RimHistogramCurve::setAppearanceFromGraphType( RimHistogramPlot::GraphType
 {
     auto fillType = graphType == RimHistogramPlot::GraphType::BAR_GRAPH ? Qt::SolidPattern : Qt::NoBrush;
     setFillStyle( fillType );
-    float transparency = graphType == RimHistogramPlot::GraphType::BAR_GRAPH ? 0.2 : 1.0;
-    setFillColorTransparency( transparency );
+    float opacity = graphType == RimHistogramPlot::GraphType::BAR_GRAPH ? 0.2 : 1.0;
+    setFillColorOpacity( opacity );
 }