contourf should support standard colormap attributes

[asinghvi17]

Currently, contourf only supports colormap and colorscale, but computes colorrange internally, i.e., the user cannot set it without jumping through hoops:

Makie.jl/src/basic_recipes/contourf.jl

Lines 73 to 79 in 65a7181

	c.attributes[:_computed_levels] = lift(c, zs, c.levels, c.mode) do zs, levels, mode
	_get_isoband_levels(Val(mode), levels, vec(zs))
	end
	colorrange = lift(c, c._computed_levels) do levels
	minimum(levels), maximum(levels)
	end

and there's no support for explicit highclip or lowclip colors.

Should we compute the levels and colorrange in calculated_attributes!(p::Contourf), and only create polygons in the recipe? Then we can expose the colorrange attribute as well.

cf. https://julialang.slack.com/archives/C8RQUU2KH/p1726592043000659