Pixiv static assets proxy worker

Usage:
  Mode A (recommended): /<host>/<path>?<query>
  Mode B (simpler):     /<path>?<query>   (defaults to s.pximg.net)
Examples:
  /s.pximg.net/accounts/assets/lang.zh.xxxx.js
  /accounts/assets/lang.zh.xxxx.js
  /i.pximg.net/user-profile/img/.../xxx_170.jpg

Allowed hosts:
  s.pximg.net, i.pximg.net, www.gstatic.cn, www.recaptcha.net, www.googletagmanager.com