feat: Allow users to pass a custom headers URL via env var npm_config_electron_mirror (#8785)

Author: lamawithonel

.changeset/fresh-phones-return.md

@@ -0,0 +1,5 @@
+---
+"app-builder-lib": patch
+---
+
+feat: Allow users to pass a custom electrons headers URL via env var

packages/app-builder-lib/src/util/yarn.ts

@@ -72,7 +72,7 @@ export function getGypEnv(frameworkInfo: DesktopFrameworkInfo, platform: NodeJS.
   // https://github.com/nodejs/node-gyp/issues/21
   return {
     ...common,
-    npm_config_disturl: "https://electronjs.org/headers",
+    npm_config_disturl: common.npm_config_electron_mirror || "https://electronjs.org/headers",
     npm_config_target: frameworkInfo.version,
     npm_config_runtime: "electron",
     npm_config_devdir: getElectronGypCacheDir(),