connectors: Add a chamfer to holes that are created

[crpalmer]

Is your feature request related to a problem? Please describe.
I use dowel connectors when I split parts and a chamfer would make it much easier to insert the dowels.

Describe the solution you'd like
Add an option for a chamfer size when creating the holes. Alternatively, just always create a small chamfer (0.4mm?) which would also address any issues with undersized holes on the build plate.

Describe how it would work
I think that's pretty straightforward.

Describe alternatives you've considered
n/a

Additional context
n/a

[jkotowicz1]

+1. Both holes and pins (dowels) needs chamfer. With right tolerances (I tried 0.5mm in depth just to be safe, and 0.15mm in diameter) the parts and dowels can be press-fitted and they hold parts pretty well without glue in most cases. But I have to model my dowels (pins) in CAD and add chamfer, because without it they don't fit in openings - the dowels (and holes, if the part is placed on cut) have elephant foot and or rest of brim.