feat: add plus-lighter support for mix-blend-mode

[Cherry]

This PR adds support for plus-lighter to mix-blend-mode, which allows for real DOM cross-fading.

This new blend mode is supported in Safari, will ship in Chrome 100, and Firefox soon.

For more information:

• https://jakearchibald.com/2021/dom-cross-fade/
• [css-compositing-2] Add plus-lighter to mix-blend-mode and background-blend-mode w3c/fxtf-drafts#444

[reinink]

@Cherry Hey this is cool, and I see the value in adding this to Tailwind, but just not quite yet, since it's not actually supported in any browsers yet.

I'm going to close this for now, but we can definitely revisit this in a few months when this feature is actually available in a few browsers 👍

[Cherry]

Understood, thanks! I'll circle back in a couple of months, as it's set to land in Chromium next week, and Firefox 99 next month from the looks of things. 👍 It's also already supported in Safari.

[reinink]

@Cherry That would be great! Thanks.