Rename React-Codegen to ReactCodegen

[dmytrorykun]

Summary: This diff renames React-Codegen to ReactCodegen. This way we'll no longer have to try both

#include <React-Codegen/MyModule.h>

and additionally

#include <React_Codegen/MyModule.h>

for cases with use_frameworks.

Differential Revision: D54068492

[facebook-github-bot]

This pull request was exported from Phabricator. Differential Revision: D54068492

[analysis-bot]

Platform	Engine	Arch	Size (bytes)	Diff
android	hermes	arm64-v8a	17,935,069	+8
android	hermes	armeabi-v7a	n/a	--
android	hermes	x86	n/a	--
android	hermes	x86_64	n/a	--
android	jsc	arm64-v8a	21,293,281	-3
android	jsc	armeabi-v7a	n/a	--
android	jsc	x86	n/a	--
android	jsc	x86_64	n/a	--

Base commit: 767330f21885e668bc0d9b5b3063113d0446bcbc Branch: main

[cortinico]

6549216b765b850a5751075ce270fcb78e76b778