Debug build image collaboration with PHP internals

This has been discussed several times already (#530, #709, #879, and #1364), and I think it's worth discussing again in light of a recent request posted to the PHP internals mailing list.

I can't speak for the entire PHP internals community, but I can say that PHP internals resources are stretched thin, and so we (speaking primarily for myself, though I'm sure others share this sentiment) are incredibly grateful to the community here at docker-library/php for providing and maintaining these images. This is an incredibly valuable resource for the greater PHP community. Thank you!

Since internals has limited resources and expertise in this area, I'd like to gauge this community's (i.e., docker-library/php) interest in collaborating with PHP internals to provide images with debug symbols. These images will be extremely helpful for those testing, performing QA, reporting bugs, reproducing bugs, etc. Since you already have the infrastructure and expertise in creating and maintaining these images, it would significantly reduce the burden on PHP internals to maintain.

The full discussion thread for this is available here: https://news-web.php.net/php.internals/125386

Instructions for joining and posting to the mailing list are available here, if you'd like to chime in: https://www.php.net/mailing-lists.php

Thanks for considering this!

Review the prior discussions in issues #530, #709, #879, and #1364, then read the linked PHP internals mailing-list thread. The issue needs agreement on collaboration and a concrete scope for debug-symbol images before implementation can begin; done is not defined in the current request.