The way to get all your binaries to be signed

[universeroc]

• Version:
  electron-builder: 20.43.0

electron-updater: 4.0.6

• Target:
  target: Windows 10

This is the a related issue of #3995

I read the source code of winPacker.ts and get some useful infomation:

• set the "signDlls": true
• _fsExtraP().readdir can not read recursively

I try some code to replace the _fsExtraP().readdir to make it could recursively read the directory and it works, but I don't know and I'm not sure how to make the recursive readdir a good one to contribute into the source code, so I open this issue @develar

`
const { promisify } = require('util');
const { resolve } = require('path');
const fs = require('fs');
const readdir = promisify(fs.readdir);
const stat = promisify(fs.stat);

  async function getFiles(dir) {
    const subdirs = await readdir(dir);
    const files = await Promise.all(subdirs.map(async (subdir) => {
      const res = resolve(dir, subdir);
      return (await stat(res)).isDirectory() ? getFiles(res) : res;
    }));
    return files.reduce((a, f) => a.concat(f), []);
  }

 const outResourcesDir = path.join(packContext.appOutDir, "resources", "app.asar.unpacked");
  // yield _bluebirdLst().default.map((0, _promise().orIfFileNotExist)((0, _fsExtraP().readdir)(outResourcesDir), []), file => {
  yield _bluebirdLst().default.map((0, _promise().orIfFileNotExist)((0, getFiles)(outResourcesDir), []), file => {
    console.log('file:', file)
    if (file.endsWith(".exe") || file.endsWith(".dll")) {
      return _this5.sign(path.join(outResourcesDir, file));
    } else {
      return null;
    }
  });

`

In my project there are several binaries in the resources/app.asar.unpacked/xxx/yyy/zzz/*.dll

So it should support readdir recursively to get the unpacked binaries to be signed, and I read this develar@66ee8ab