RN: Enforce Manifest Constraints w/ ESLint (#39064)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/39064

Creates a new lint rule that enforces the following constraints:

- `react-native/monorepo` cannot have `dependencies`.
- `react-native` cannot have `devDependencies`.

This also includes a lengthy comment in the rule definition explaining why these constraints exist, so that future contributors can make an informed decision when reconsidering these constraints.

Changelog:
[Internal]

Reviewed By: NickGerleman

Differential Revision: D48448633

fbshipit-source-id: 26b0d74b9120ddfd2a6a72bb91f86a98c8d679ef