Take into account color and unicode in matrix alignment

[Keno]

Without this, alignment would count characters rather than
textwidth as well as counting inline escape sequences in
colored output. Fix that by using uncolored printing for
alignment and textwidth rather than number of codepoints.

[Keno]

Test failure is because the branch is missing #45670.

[YingboMa]

Can this get backported?

[mcabbott]

Can this be done for Diagonal, etc? They use length(s) at the moment:

julia/stdlib/LinearAlgebra/src/diagonal.jl

Lines 136 to 138 in 7212c03

	function Base.replace_in_print_matrix(A::Diagonal,i::Integer,j::Integer,s::AbstractString)
	i==j ? s : Base.replace_with_centered_mark(s)
	end

julia/base/arrayshow.jl

Lines 42 to 45 in 8af6731

	function replace_with_centered_mark(s::AbstractString;c::AbstractChar = '⋅')
	N = length(s)
	return join(setindex!([" " for i=1:N],string(c),ceil(Int,N/2)))
	end

and get a string from print_matrix_row. So either print_matrix_row has to pass them more information, or we need something like textwidth which strips colour codes.