Blender Git Loki

Make loopcut drawing consistent between gizmo and operator.

Loopcut drawing from gizmo had thicker lines because
it was using line smoothing without alpha blend, compared
to thin jagged lines from operator.

Make the drawing anti aliased and consistent by using
3D_POLYLINE/3D_POINT shaders, and making sure alpha
blending is on.

Reviewed By: #eevee_viewport, fclem

Differential Revision: https://developer.blender.org/D11333