Concept: Use an internal development test kit instead of relying on special dev_suite workarounds [DO NOT MERGE]

[arscan]

The purpose of this PR is to demonstrate the concept so we can decide if its worth implementing properly.

We put in the 'dev_suites' thing forever ago, and hotwired some things to just make it work. I think we've outgrown it.

I think we should move to a setup where we just have a test kit, isolated to a top-level directory and not included in the inferno_core gem, that we use for internal development. I'm not sure if this is quite right -- I basically had claude do this for me while multi-tasking. However, it broadly seems to work. I am just putting it in here to demonstrate the concept; not because it is fully working.

This will also allow us to develop the test kit landing page more easily, instead of polluting inferno core with more development-specific workarounds. I think implementing this quickly would be less work than adding in more workarounds to help us develop the test kit landing page.

It also gets things that are unrelated to inferno_core out of the base directory, like 'config' and 'data'. There are probably a lot more test-kit-y things in the base directory, I didn't bother clearing those out. But, for all those test kit things that exist to provide a environment to develop against, it makes sense to me to have them all within a directory instead of being comingled with inferno_core specific things.

Yes, this is yet another copy of a test kit to update. But, i believe the diff on it would be a driving diff for updating all test kits. And whats another 1 when we have 30+ to maintain already?