Better location setting ability for basewidget in pie chart .

**Feature description**
I want text widget to be displayed inside the pie chart but I am unable to adjust its position aside from offset from center.

**Describe the solution you'd like**
I would love to be able to give angle offset relative to the title location .

Start with the pie chart BaseWidget and trace how the text widget's current offset from the center and the title location are handled. Determine how an angle offset relative to the title should be represented, then add coverage showing the text can be positioned with that offset and verify the resulting chart layout.

Written by the indexing model from the issue text.