RFC: add custom command line switches? (eg --network host)

[pataquets]

This time, I need to add the --network host switch, and there's no specific defcustom.
However, given the long list of docker build command line switches, I'm wondering if some kind of dockerfile-build-extra-options kind of defcustom would be a better solution for more uncommon options.
Note that I'm not advocating against adding more specific and meaningful dockerfile-build-* options, which would be the best most of the times.
But having to think about an implementation and sending a PR is quite more involved and there's the risk of users "just hacking" the package. Specially if you need a switch temporarily or as a test, before you settle on using it more frequently and you're up to giving the switch some love with a PR.
@drewcsillag WDYT? Any advice/hint before sending the PR? (eg. defcustom name)

[drewcsillag]

Sorry for the delay! I like this idea. Better than having a zillion defcustoms for random things.

[pataquets]

Happy to hear that, @drewcsillag.
I've just opened PR #88.