refactor(rest): switch api to fetch-like and provide strategies (#9416)

BREAKING CHANGE: NodeJS v18+ is required when using node due to the use of global `fetch`
BREAKING CHANGE: The raw method of REST now returns a web compatible `Respone` object.
BREAKING CHANGE: The `parseResponse` utility method has been updated to operate on a web compatible `Response` object.
BREAKING CHANGE: Many underlying internals have changed, some of which were exported.
BREAKING CHANGE: `DefaultRestOptions` used to contain a default `agent`, which is now set to `null` instead.

packages/rest/README.md

@@ -23,7 +23,7 @@
 
 ## Installation
 
-**Node.js 16.9.0 or newer is required.**
+**Node.js 18.12.0 or newer is required.**
 
 ```sh
 npm install @discordjs/rest
@@ -80,6 +80,25 @@ try {
 }
 ```
 
+Send a basic message in an edge environment:
+
+```js
+import { REST } from '@discordjs/rest';
+import { Routes } from 'discord-api-types/v10';
+
+const rest = new REST({ version: '10', makeRequest: fetch }).setToken(TOKEN);
+
+try {
+	await rest.post(Routes.channelMessages(CHANNEL_ID), {
+		body: {
+			content: 'A message via REST from the edge!',
+		},
+	});
+} catch (error) {
+	console.error(error);
+}
+```
+
 ## Links
 
 - [Website][website] ([source][website-source])