Add snap after-package repack script

scripts/prepare-release.ts

@@ -1,36 +1,7 @@
 import * as fs from 'fs-extra'
 import * as path from 'path'
-import { spawn, ChildProcess } from 'child_process'
 import { chdir } from 'process'
-
-async function exec(cmd: string, args: string[] = []) {
-  const child = spawn(cmd, args, { shell: true })
-  redirectOutputFor(child)
-  await waitFor(child)
-}
-
-function redirectOutputFor(child: ChildProcess) {
-  const printStdout = (data: Buffer) => {
-    process.stdout.write(data.toString())
-  }
-  const printStderr = (data: Buffer) => {
-    process.stderr.write(data.toString())
-  }
-  child.stdout.on('data', printStdout)
-  child.stderr.on('data', printStderr)
-
-  child.once('close', () => {
-    child.stdout.off('data', printStdout)
-    child.stderr.off('data', printStderr)
-  })
-}
-
-async function waitFor(child: ChildProcess) {
-
-  return new Promise((resolve) => {
-    child.once('close', () => resolve())
-  })
-}
+import { exec } from './util';
 
 const targetDir = path.join('build', 'clean')
 async function prepareRelease() {