static_show: Don't print field names of structs in --trace-compile output

[topolarity]

This is a revival of #40652, to remove spurious reasons that --trace-compile output does not eval properly right now (I don't know if we'll be able to fix all of the flaws, but it seems worthwhile to fix the easy cases so that we can focus on the hard ones)

The default REPL printing does not think it's worth printing these field names:

julia> struct Foo
           x::Int
           y::Int
           z::Int
       end

julia> Foo(1,2,3)
Foo(1, 2, 3)

so I'm not sure why our static_show would find it necessary.

[topolarity]

@vtjnash if you really want these field names and also don't want them printed as a comment (e.g. Foo(#= x =# 1, #= y =# 2, #= z =# 3)), I'll happily add this as a printing option in the config / context

[vtjnash]

Debugging relies very heavily on these field names, so NAK any removal of them (it also makes the correct version of precompile worse, since it can no longer use those comments to try to construct the new object correctly)

[topolarity]

Any complaint if they are printed as comments?

[topolarity]

Added a config option. jl_ now prints:

julia> ccall(:jl_, Cvoid, (Any,), Foo(1,2,3))
Main.Foo(#= x =# 1, #= y =# 2, #= z =# 3)

And --trace-compile prints:

precompile(Tuple{typeof(Main.foo), Base.Val{Main.Foo(1, 2, 3)}})

[vtjnash]

Eh, it looks worse and makes implementing the good version much harder, but it is valid

[topolarity]

@vtjnash Some time has passed and I still think we need to print accurate types to the user for --trace-compile

If you'd like to make the precompile(...) de-serializer type-imprecise, I'm fine with that but I think it needs to done on the de-serializer side. It's just too valuable to have a precise serializer to report types to the user

I'll merge this in the next day, unless you have any objections.

[vtjnash]

I still object to this process of making our serializer less correct and worse implemented instead of fixing our deserializer design problems