`glyph.insertContour()` would be nice

[ryanbugden]

After some discussion in the RoboFont discord...
https://discord.com/channels/1052516637489766411/1160926838365880330
...it became clear that manipulating indices of contours in a glyph can be tricky without recompiling all of the contours in the whole glyph in the desired order.

Would it make sense or be possible to have, like font.insertGlyph() or font.insertLayer(), there could be a glyph.insertContour(contourObject, index=0) or something like that?