chore: update package.json scripts for gn build and automated releases (#14612)

* Removes un-used and non-functional code coverage helpers
* Removes un-used release script aliases
* Moves TLS to a lib folder for cleaner directory structure
* Implements start.py as start.js for the GN build
* Adds a re-usable getElectronExec helper for future scripts
* Refactors spec runner to use the helper

script/lib/utils.js

@@ -0,0 +1,26 @@
+const OUT_DIR = process.env.ELECTRON_OUT_DIR || 'Default'
+
+const path = require('path')
+
+function getElectronExec () {
+  switch (process.platform) {
+    case 'darwin':
+      return `out/${OUT_DIR}/Electron.app/Contents/MacOS/Electron`
+    case 'win32':
+      return `out/${OUT_DIR}/electron.exe`
+    case 'linux':
+      return `out/${OUT_DIR}/electron`
+    default:
+      throw new Error('Unknown platform')
+  }
+}
+
+function getAbsoluteElectronExec () {
+  return path.resolve(__dirname, '../../..', getElectronExec())
+}
+
+module.exports = {
+  getElectronExec,
+  getAbsoluteElectronExec,
+  OUT_DIR
+}