Move to react-icons v3

[codercatdev]

Is your feature request related to a problem? Please describe.

It is difficult to use icons that are on a new version.
Example: https://react-icons.netlify.com/#/icons/io

I would like to use things like FaHighlighter which are not offered in the older version of react-icons.

Describe the solution you'd like

Implement package react-icons@3.7.0 @sanity/base

Describe alternatives you've considered

I have tried adding them manually in my project, but I then have to override everything.

Additional context

[Grsmto]

They should rather move away from react-icons or somehow update Webpack, cause of this issue, react-icons causes Sanity Studio js bundle to be more 4mb.
I guess this probably slows down massively the initial loading of the Studio on mobile devices.

[rexxars]

In version v2.0.1 and later we no longer bundle react-icons as part of the studio, and you're free to use any version of this library (or other icon libraries) you want: https://github.com/sanity-io/sanity/releases/tag/v2.0.1