Port the widget to select the chart subtype in the "Chart Type"
dialog from using a ValueSet widget to using weld::IconView.
This helps to be more consistent with other platform/toolkit
widgets and reduces custom logic.
Adjust indices used to account for the fact that
weld::IconView indices are 0-based while the ValueSet ones
are 1-based.
The dialog can be triggered like this:
* start Writer
* insert a chart using "Insert" -> "Chart..."
* right-click on one of the bars in the chart to open
the context menu
* activate the "Chart Type..." menu item
The chart sidebar (ChartTypePanel) will also be ported
in an upcoming commit.
Change-Id: I188f812f2d03fa8cbd97ffaaab3081094809887e
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/211658
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>