Add and Remove corresponding classes to capture higher contrast/print friendly png and jpg exports (#2088)

* add and remove corrensponding class to capture better images (wip)

* pass class through exportAsPng and exportAsJpg directly

* pass classname from stacked plots into exportImageService

* Adding additional export styles

Fixes #2088
- WIP

* WIP export styles

Fixes #2080
- Styling WIP;
- Moved styles into plots-main.scss;
- Change to how plot hashes are rendered;

* add class before clone, because adding it on clone was not rendering new css styles

* Export styles

Fixes #2080
- Code indenting cleaned up;
- Additional styles for export;
- Added hide effects for .h-local-controls and unsynced state;

* Apply class to cloned element only

platform/commonUI/themes/snow/res/sass/_constants.scss

@@ -183,7 +183,8 @@ $colorTabHeaderBorder: $colorBodyBg;
 // Plot
 $colorPlotBg: rgba(black, 0.05);
 $colorPlotFg: $colorBodyFg;
-$colorPlotHash: $colorTick;
+$colorPlotHash: black;
+$opacityPlotHash: 0.2;
 $stylePlotHash: dashed;
 $colorPlotAreaBorder: $colorInteriorBorder;
 $colorPlotLabelFg: pushBack($colorPlotFg, 20%);