Feature/delegate to first font in fallback list on React Native

[Jta26]

In working with some internal stuff, I needed to do a pretty gnarly code-split between Web, Android, and iOS due to different platforms having different names for their fonts. In addition, I needed to do !important on web to override a bunch of high specificity styles in a global CSS file. When I added !important, I noticed the incompatibility here.

!important is being sent down through an html.span to the underlying <Text>'s TextStyleProps in RN, resulting in an undefined font family. RSD will also send down fallback fonts, also resulting in undefined fonts. Ideally !important is never used in atomic styles, but in the event that it is used, I think it's reasonable to strip it off completely.

Example:

Thought I'd try to throw up a PR that fixes it.

Two Questions

1. Should we change this to always strip off !important for all CSS properties? There is no value in doing anything with !important on native imo.
2. Is delegating to the first font in the list of fallbacks the right thing to do here? Should we do a runtime check on font's somehow to support proper fallbacks?

Snapshot tests written by AI

[Jta26]

Synced offline, updated this PR to not do anything with !important, but it will still handle delegating to the first font in the list of fallbacks on React Native.