Round-trippable show for Bidiagonal (#55347)

This changes how a `Bidiagonal` is displayed using the 2-arg `show` to a
form that may be parsed.
After this,
```julia
julia> B = Bidiagonal([1,2,3], [1,2], :U)
3×3 Bidiagonal{Int64, Vector{Int64}}:
 1  1  ⋅
 ⋅  2  2
 ⋅  ⋅  3

julia> show(B)
Bidiagonal([1, 2, 3], [1, 2], :U)
```
The displayed form is a valid constructor now.

Author: jishnub

stdlib/LinearAlgebra/src/bidiag.jl

@@ -264,12 +264,13 @@ end
 ####################
 
 function show(io::IO, M::Bidiagonal)
-    # TODO: make this readable and one-line
-    summary(io, M)
-    print(io, ":\n diag:")
-    print_matrix(io, (M.dv)')
-    print(io, M.uplo == 'U' ? "\n super:" : "\n sub:")
-    print_matrix(io, (M.ev)')
+    print(io, "Bidiagonal(")
+    show(io, M.dv)
+    print(io, ", ")
+    show(io, M.ev)
+    print(io, ", ")
+    show(io, sym_uplo(M.uplo))
+    print(io, ")")
 end
 
 size(M::Bidiagonal) = (n = length(M.dv); (n, n))

stdlib/LinearAlgebra/test/bidiag.jl

@@ -143,11 +143,9 @@ Random.seed!(1)
 
     @testset "show" begin
         BD = Bidiagonal(dv, ev, :U)
-        dstring = sprint(Base.print_matrix,BD.dv')
-        estring = sprint(Base.print_matrix,BD.ev')
-        @test sprint(show,BD) == "$(summary(BD)):\n diag:$dstring\n super:$estring"
+        @test sprint(show,BD) == "Bidiagonal($(repr(dv)), $(repr(ev)), :U)"
         BD = Bidiagonal(dv,ev,:L)
-        @test sprint(show,BD) == "$(summary(BD)):\n diag:$dstring\n sub:$estring"
+        @test sprint(show,BD) == "Bidiagonal($(repr(dv)), $(repr(ev)), :L)"
     end
 
     @testset for uplo in (:U, :L)