Refactor plot actions to save space

[shefalijoshi]

Closes #4359

Describe your changes:

Move plot export PNG and JPG actions to the 3-dot menu.
Move plot toggle cursor and gridlines to the plot local controls section.

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• Is this change backwards compatible? For example, developers won't need to change how they are calling the API or how they've extended core plugins such as Tables or Plots.

Author Checklist

• Changes address original issue?
• Unit tests included and/or updated with changes?
• Command line build passes?
• Has this been smoke tested?
• Testing instructions included in associated issue?

Reviewer Checklist

• Changes appear to address issue?
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[codecov]

Codecov Report

Merging #5201 (f86c18b) into master (1ca5271) will decrease coverage by 0.04%.
The diff coverage is 37.14%.

@@            Coverage Diff             @@
##           master    #5201      +/-   ##
==========================================
- Coverage   50.21%   50.17%   -0.05%     
==========================================
  Files         546      548       +2     
  Lines       20071    20101      +30     
  Branches     1859     1859              
==========================================
+ Hits        10079    10085       +6     
- Misses       9508     9531      +23     
- Partials      484      485       +1     

Impacted Files	Coverage Δ
src/exporters/ImageExporter.js	34.78% <ø> (ø)
src/plugins/plot/Plot.vue	38.46% <0.00%> (+2.74%)	⬆️
src/plugins/plot/PlotViewProvider.js	76.19% <0.00%> (-12.70%)	⬇️
...lugins/plot/overlayPlot/OverlayPlotViewProvider.js	14.28% <0.00%> (-3.90%)	⬇️
src/plugins/plot/stackedPlot/StackedPlot.vue	44.18% <0.00%> (-5.82%)	⬇️
...lugins/plot/stackedPlot/StackedPlotViewProvider.js	14.28% <0.00%> (-3.90%)	⬇️
src/plugins/plot/MctPlot.vue	52.00% <28.57%> (-0.31%)	⬇️
src/plugins/plot/stackedPlot/StackedPlotItem.vue	68.42% <50.00%> (-2.17%)	⬇️
src/plugins/plot/actions/ViewActions.js	75.00% <75.00%> (ø)
src/plugins/plot/actions/utils.js	100.00% <100.00%> (ø)
... and 3 more

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[charlesh88]

LGTM with these changes:

• Moved cursor guides and grid toggle buttons.
  
• Fixed typo and improved image export dialog message.

[michaelrogers]

This refactor looks good to me. The moved controls and png+jpg download work as expected when tested locally.

[davetsay]

Good stuff