undo breaking change of removing `parent` field from CodeInfo (#53393)
This drops the unnecessary breaking change from
https://github.com/JuliaLang/julia/pull/53219 by re-adding the optional
`parent` field to CodeInfo. A few months ago, I had actually already put
together a branch that also fixed Keno's complaints about how it was not
set reliably, so I copied that code here also, so that it should get set
more reliably whenever a CodeInfo is associated with a MethodInstance
(either because it called `retrieve_code_info` to get IR from the Method
or `uncompress_ir` to get it from the inference cache). This does not
entirely fix Cthulhu's test errors, since I don't see any particular
reason to re-introduce the other fields (min_world, max_world, inferred,
edges, method_for_inference_limit_heuristics) that got removed or are
now set incorrectly, and most errors appear to be instead related to the
`Expr(:boundscheck, true/false)` change. However, they could be
trivially re-added back as placeholders, if someone encounters a broken
package that still needs them.
julia
962d8335 - undo breaking change of removing `parent` field from CodeInfo (#53393)
