debugging: Add `jl__` utility for high-verbosity printing (#61060)
As seen on https://github.com/JuliaLang/julia/pull/60975, we don't have
a very consistent "intent" when printing via `jl_`:
Some objects such as MethodInstances print almost none of their fields,
while others such as CodeInstances print almost everything, even if it
means flooding your terminal. This PR attempts to solve this problem by
adding `jl__` which is high-verbosity and tries to print "all" data
structurally accessible from an object.
This allows `jl_` printing to be tweaked to a more "reasonable" default
for general inspection / printing of objects during runtime debugging,
more analogous to `Base.show()` rather than `Base.dump()`.
(no actual printing differences are added in this PR, but hopefully this
will make https://github.com/JuliaLang/julia/pull/60975 more
straightforward to finish)
julia
4c2e9b7d - debugging: Add `jl__` utility for high-verbosity printing (#61060)
