[prettier] Combine compiler and runtime configs

Merges the existing config to the root one so we can have a single
configuration file. I've tried to keep the compiler config as much as
possible in this PR so that no formatting changes occur.

ghstack-source-id: 8bbfc9f269c4b2d740803937a4f2401d44cce9e4
Pull Request resolved: https://github.com/facebook/react/pull/30021