Cartesian isapprox should do vector comparison instead of elementwise comparison

isapprox(::Cartesian, ::Cartesian) currently fails for points with lon ≈ ±90° (e.g. Memphis, Tennessee).

julia> r = convert(Cartesian, LatLon(0,0)).x
6.378137e6 m

julia> convert(Cartesian, LatLon(0, 90)) ≈ Cartesian{WGS84Latest}(0u"m", r, 0u"m")
false

The problem is that isapprox(::Cartesian, ::Cartesian) currently compares every entry one by one for approximate equality.

CoordRefSystems.jl/src/crs/basic.jl

Lines 61 to 65 in 14940f9

    
           function Base.isapprox(coords₁::C, coords₂::C; kwargs...) where {C<:Cartesian} 
        
             tup₁ = _coords(coords₁) 
        
             tup₂ = _coords(coords₂) 
        
             all(isapprox(c₁, c₂; kwargs...) for (c₁, c₂) in zip(tup₁, tup₂)) 
        
           end

Instead, it should do a vector comparison, isapprox(x::Cartesian, y::Cartesian) = norm(x - y) / max(norm(x), norm(y)), analogous to how Base does it.

	function Base.isapprox(coords₁::C, coords₂::C; kwargs...) where {C<:Cartesian}
	tup₁ = _coords(coords₁)
	tup₂ = _coords(coords₂)
	all(isapprox(c₁, c₂; kwargs...) for (c₁, c₂) in zip(tup₁, tup₂))
	end