Tests: use minimal configuration by default

[mg979]

Previously, when running PlenaryBusted commands, all plugins were being loaded.

{ minimal = true } wouldn't work either because plenary must be loaded, --noplugin would prevent that.

{ minimal_init = path } had the same problem.

Solution:

• minimal by default
• minimal and minimal_init are still recognized and will have the effect of adding the --clean argument, but most of the times they can be omitted
• minimal_init will still be sourced
• minimal is the same as no options, so it can be omitted
• additional 'init' option, that doesn't use --clean
• in any case, plenary directory is always added to the rtp, so no need for the user to do that

I couldn't make it work in Windows though (neither before).

[mg979]

I kept minimal and minimal_init for backwards compatibility, but imho they're cruft. It would be better to have a single args key, accepting a table with extra arguments, and just use --clean when it's not given.
Plugin directory would be added to the rtp regardless.

[Conni2461]

yeah i kinda wanna keep backwards compatibility. No real need to a breaking change here.

thanks for the PR :) can you fix the stylua ci? thanks

[mg979]

I fixed it by the way. I also tested the PR against nvim-lint and null-ls.nvim tests and it was ok.

[Conni2461]

thanks :)

[Conni2461]

using --clean here is a breaking change, we need to continue to use --noplugin, see #497

[wookayin]

This was reverted in #497. So for now, as per #497 we will use user's init.lua but without plugins, which is kind of weird setup (see #497 (comment)).

Can we have this back again?