Move version comment to a plugin of its own to lose the preFlight dependency

[willdean]

At the moment, you only get a version comment at the top of the TW output if you're using preFlight.
To me, the use (or not) of the preFlight and the value of a version comment are orthogonal - the former is sometimes useful, sometimes not. The latter is always a nice thing to have, and I miss it on non-preFlighted projects.

I tentatively propose adding a new plugin "versionComment" at the top of the corePlugins object, something like this:
(I am not God's Gift to TW plugin authorship so this may be embarrassingly bad)

 versionComment: ({ addBase  })=>{
        addBase([
            _postcss.default.comment({
                text: `! tailwindcss v${_packageJson.version} | MIT License | https://tailwindcss.com`
            })
        ]);
    },

And then removing the existing code which generates the comment from the preFlight plugin.

One also has to add "versionComment" at the top of the list of core plugins in corePluginList.js

Is this something which might be considered if I submitted a PR?

[MichaelAllenWarner]

Not sure if a separate plugin is the right solution, but I'm bumping this because I agree that the license-comment should appear even if you have preflight disabled.

Here is a Tailwind Play link with preflight disabled, and you can see that there's no license-comment at the top of the Generated CSS: https://play.tailwindcss.com/nPTMCxCuB5?file=config