conversion traits not taken into account in 0.21

[aplavin]

In 0.21, convert_argument(trait, args...) methods are not really called with user-specified arguments.
That's due to the new expand_dimensions function called before convert_arguments with conversion trait:

Makie.jl/src/conversions.jl

Lines 17 to 21 in d157f9c

	CT = conversion_trait(T, args...)
	# Try to expand dimensions first, as this is the most basic step!
	expanded = expand_dimensions(CT, args...)
	!isnothing(expanded) && return convert_arguments(T, expanded...; kw...)

.

Noticed when trying to update KeyedArray conversions (in AxisKeysExtra.jl) to the new Makie version, specifically conversions like https://github.com/JuliaAPlavin/AxisKeysExtra.jl/blob/0000000065d69673f7f40c0f93f01ba0fbbbda34/ext/MakieExt.jl#L10-L13. MWE:

julia> using AxisKeys, Makie

julia> Makie.convert_arguments(ct::PointBased, x::KeyedArray{<:Any,1}) = convert_arguments(ct, only(axiskeys(x)), AxisKeys.keyless_unname(x))

julia> convert_arguments(Scatter, KeyedArray([1,2,3], x=10:10:30))
# 0.20, expected:
(Point{2, Float32}[[10.0, 1.0], [20.0, 2.0], [30.0, 3.0]],)
# 0.21, unexpected:
(10:10:30, Point{2, Float64}[[1.0, 1.0], [2.0, 2.0], [3.0, 3.0]])

• are you running newest version (version from docs) ? bug only appears in 0.21, while 0.20 works fine
• can you reproduce the bug with a fresh environment ? (]activate --temp; add Makie)
• What platform + GPU are you on? any platform