Adds a new function MolDraw2D_detail::getSGroupDataLabels() that returns
the text and molecule-coordinate positions of DAT SGroup labels, using
the same placement logic as the drawing code. This allows external
renderers to display SGroup labels consistently with RDKit's placement.
Refactors DrawMol::extractSGroupData() to call getSGroupDataLabels()
internally, eliminating the duplicate FIELDDISP parsing and position
computation logic.
Closes#7829
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
d8f4afb558