More test discovery and better interfaces

[psionic-k]

I'm still avoiding heavier packages that concern themselves with dependencies and sandboxing. Nix and CI do sandboxing and dependencies. A user can use Nix locally to reproduce that. It's only getting better as Emacs accepts flags to use a different home directory.

What remains though is how to find tests, and how to run them. I think there needs to be just one shim for discovery the load paths. I'm not decided about passing arguments to --script versus keeping individual scripts. I don't like having four files in test/

For entry points, using --script can accept options and the argument stripping used now is consistent. I don't want to rely on long invocations like emacs --eval '(require something)'.

Make seems to fit well with documenting commands and providing shorthands. I don't want to use more shell or make to accomplish what can be done in elisp, keeping the focus on elisp development.

Better interfaces

More Emacs commands are needed. It seems like reloading via unload-feature and require when the load paths are configured is fine. There could be some discovery and use of compiling in the case that straight or another package manager are known to be managing the load path.

Test discovery can also benefit from some streamlining. It would be great to be able to reload the feature and run a test without going through 4-5 manual steps on 2-3 different buffers.