Breaking - Bump minimum Node version from 16 to 18 (#37709)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/37709

## Bump minimum Node JS version to 18 via `react-native/package.json#engines`

In https://github.com/facebook/react-native/pull/35443 we bumped up the node version from 16 to 18.

Node 16 [ends maintenance releases on 2023-09-11](https://nodejs.org/en/blog/announcements/nodejs16-eol/), and bumping this minimum will allow other associated Node JS tools (CLI, Metro, Jest) to reduce their support burden.

This follows up by formally making Node 18 the minimum supported version.

**Docs PR:**
https://github.com/facebook/react-native-website/pull/3748

**Changelog:**
[General][Breaking] Bump minimum Node JS version to 18

Reviewed By: yungsters

Differential Revision: D46462639

fbshipit-source-id: d3b607788f596e8b5a9c4a6855d3b2f4bafe9a7a