ONL-5955: Update to postcss8

[mcibique]

Postcss 8 introduced lots of breaking changes and not a single plugin is compatible so we had to wait until everybody upgrades. Unfortunately, postcss-preset-env wasn't unable to do that even today because it contains 30+ other postcss plugins. Because we don't use any syntax from postcss-preset-env, I decided to remove the plugin from chameleon and EBO. So did other projects.

Updated Tailwind to version 2 and updated config. The changelog is huge but it affects us only in few places:

1. filters have been added to TW, so the tailwind-filters plugin is no longer needed. The filters have been used only in one place in chameleon, 0 in EBO so it was safe to migrate.
2. TW2 has some issues when used directly inside of a postcss-mixin. There is a workaround mentioned in this issue.
3. Tailwind's transformations have been reworked and they cannot be used in the animations anymore. It broke spin animation for loading icons.

[vercel]

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