feat(APIRequest): support setting global headers in HTTPOptions (#5586)

Co-authored-by: Vlad Frangu <kingdgrizzle@gmail.com>

src/rest/APIRequest.js

@@ -33,7 +33,7 @@ class APIRequest {
         ? this.client.options.http.api
         : `${this.client.options.http.api}/v${this.client.options.http.version}`;
     const url = API + this.path;
-    let headers = {};
+    let headers = { ...this.client.options.http.headers };
 
     if (this.options.auth !== false) headers.Authorization = this.rest.getAuth();
     if (this.options.reason) headers['X-Audit-Log-Reason'] = encodeURIComponent(this.options.reason);

src/util/Constants.js

@@ -80,6 +80,7 @@ exports.DefaultOptions = {
    * @property {string} [cdn='https://cdn.discordapp.com'] Base url of the CDN
    * @property {string} [invite='https://discord.gg'] Base url of invites
    * @property {string} [template='https://discord.new'] Base url of templates
+   * @property {Object} [headers] Additional headers to send for all API requests
    */
   http: {
     version: 8,