Add snap after-package repack script

scripts/afterPack.ts

@@ -0,0 +1,22 @@
+import * as fs from 'fs-extra'
+import * as path from 'path'
+import { chdir } from 'process'
+import { exec } from './util'
+
+export default async function (info: any) {
+  for (const snapFile of info.artifactPaths) {
+    if (/\.snap$/.test(snapFile)) {
+      const originalDir = __dirname
+      const dirname = path.dirname(snapFile)
+      chdir(dirname)
+
+      await exec('sudo', ['unsquashfs', snapFile])
+      await fs.remove(snapFile)
+      await exec('sudo', ['chmod', '-R', 'g-s', 'squashfs-root'])
+      await exec('sudo', ['snapcraft', 'pack', 'squashfs-root', '--output', snapFile])
+      await fs.remove('squashfs-root')
+
+      chdir(originalDir)
+    }
+  }
+}