Better support for portals & CSS-in-JS

[OlegWock]

Currently (because of mutation observer), it's possible to have FOUC when using CSS-in-JS because styles are copied with small delay. It might be good idea to implement custom Sheet and Tag to support multiple targets for injection.

Related:

https://github.com/styled-components/styled-components/blob/main/packages/styled-components/src/sheet/Sheet.ts#L78C41-L78C41
https://github.com/styled-components/styled-components/blob/main/packages/styled-components/src/sheet/Tag.ts#L5

[OlegWock]

Fixes for styles-components, still need to work on emotion

Probably will need to implement custom cache https://github.com/emotion-js/emotion/blob/main/packages/cache/src/index.js