improve setproperties() error message

[aplavin]

Currently, it can be both too long and unclear for novices (I saw some confusion), eg:

ERROR: The function Base.propertynames was overloaded for type Mesh{3, Float32, GeometryBasics.Ngon{3, Float32, 3, Point{3, Float32}}, SimpleFaceView{3, Float32, 3, OffsetInteger{-1, UInt32}, Point{3, Float32}, NgonFace{3, OffsetInteger{-1, UInt32}}}}.
Please make sure ConstructionBase.setproperties is also overloaded for this type.

This PR changes it to:

The Mesh type defines custom properties: it has propertynames overloaded.
Please define ConstructionBase.setproperties(::Mesh, ::NamedTuple) to set its properties.

Happy to rephrase if you have other suggestions!

[jw3126]

Do we have a test that triggers this error? E.g. undefined variable sneaks in easily into error messages with string interpolation, so worth a test if we don't have already.

[aplavin]

I think so, around here:

ConstructionBase.jl/test/runtests.jl

Lines 328 to 332 in 3f1e80e

	res = @test_throws ErrorException setproperties(x, c=0)
	msg = sprint(showerror, res.value)
	@test occursin("overload", msg)
	@test occursin("setproperties", msg)
	@test occursin("FieldProps", msg)