Move observability-relevant structure fields to the top by P403n1x87 · Pull Request #105271 · python/cpython

Some structures have fields that are used by out-of-process tools, like
Austin. Having these fields defined after some more complex structures
makes it hard to maintain these tools. With this change, we move the
declaration of the most useful fields to the top of the structure
definition. This reduces the amount of irrelevant information that the
mentioned tools have to replicate to retrieve the actually useful data