cubicweb-genomics #3920719 Add left/right gene for GenomicRegion [validation pending]

prioritynormal
typebug
done in0.9.0
load0.200
load left0.000
closed by#f05ff0edc003 [schema] Add left/right gene for GenomicRegion, closes #3920719
patch[schema] Add left/right gene for GenomicRegion, closes #3920719 [applied]