Breaking - Bump minimum Node version from 16 to 18 (facebook#1002)

Summary:
Pull Request resolved: facebook#1002

X-link: facebook/react-native#37709

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

In facebook/react-native#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:**
facebook/react-native-website#3748

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

Differential Revision: D46462639

fbshipit-source-id: e1e36f7d8bedb7b1a66a6cc33a4ccc2eb62ff17f

.circleci/config.yml

@@ -10,8 +10,8 @@ references:
   # For stability, Node.js versions we run against in CI are defined explicitly
   # (the "lts" alias may bring in a future version before we support it)
   node_supported_lts_versions: &node_supported_lts_versions
-    - &node_min_supported_version "16.18"
-    - "18.12"
+    - &node_min_supported_version "18.12"
+    - "20.2"
   node_lts_image: &node_lts_image cimg/node:18.12
 
   secure_unset_publish_token: &secure_unset_publish_token