turf.convex doesn't support single or colinear points

This might be more of a feature request instead of a bug report, but I found the behaviour of turf.convex non-intuitive. I would expect something like this behaviour:

var singlePoint = turf.convex(turf.point([10, 45])); // == turf.point([10, 45])

var twoPoints = turf.featureCollection([
  turf.point([10, 45]),
  turf.point([11, 45]),
]);
var twoHull = turf.convex(twoPoints) // == turf.lineString([[10, 45], [11, 45]])  (or the other direction)

var colinearPoints = turf.featureCollection([
  turf.point([12, 45]),
  turf.point([10, 45]),
  turf.point([11, 45]),
]);
var colinearHull = turf.convex(colinearPoints) // == turf.lineString([[10, 45], [12, 45]])  (or the other direction)

My exact use-case is to use turf.convex followed by turf.buffer on a set of points, so I don't mind that the intermediate result isn't a polygon, since the final result will be. The two first cases are easy to handle (just check the number of input points), but the third one isn't as easy.

This would also potentially break code that assumes turf.convex will always return a Polygon or throw.

I'm currently at v6.5.0.

Start at the turf.convex entry point and locate its existing tests or implementation. Check how single points, two points, and colinear point collections are handled, then clarify the intended return geometry and compatibility expectations. Done means the requested degenerate-input behavior is covered for the examples in the issue without breaking existing Polygon behavior.