htmlwidget reporting updates

[jwildfire]

Summary

This PR along with SafetyGraphics/safetyGraphics#526 fixes issues in htmlwidget reporting. Including those in #49.

Now all standard renderers expect for AE Timelines should be working well in safetyGraphics reports. See #51 for a summary of the AE Timelines issues.

Test Notes.

Same as SafetyGraphics/safetyGraphics#526 - Make sure all exported charts work as expected using the following branches:

devtools::install_github("safetyGraphics/safetyCharts", ref="fix-49")
library(safetyCharts)
devtools::install_github("safetyGraphics/safetyGraphics", ref="reports-updates")
library(safetyGraphics)
safetyGraphics::safetyGraphicsApp()

[elimillera]

Per SafetyGraphics/safetyGraphics#522,

I reviewed the charts and they looked all good to me with the exception of the Hepatic Explorer

[jwildfire]

Let's make sure that hep-explorer is working for someone other than me before we merge.

@xni7 @samussiah @bzkrouse - could one of you take a quick look and see if it runs in the app and export?