Add support for Websocket endpoints

[fortuna]

This tracks the work towards supporting Websocket in the Outline client.

To Do

• Remove parseTunnelConfig implementation from Typescript, along with the remaining Shadowsocks-specific code.
  • Implement parseTunnelConfig in Go
  • Add to Apple
  • Add to Android
  • Add to Electron
• Add config support for Websocket
  • Finalize the design
  • Implement it in the Go code

Done

As you can see, we had to re-write major portions of the code. Most of the PRs below are large or extra-large.

Remove explicit dependencies on Shadowsocks from Typescript code

• refactor(client): reduce config library surface #2269
• refactor(client): more config cleanup and consolidation #2265
• refactor(client): clean up transport in Typescript #2192
• refactor(client): replace references to Shadowsocks #2182
• refactor(client): revamp Tunnel code #2072

Remove explicit dependencies on Shadowsocks across the stack

• refactor(client): preliminary wiring of service name #2075
• refactor(client): decouple Typescript VPN API from individual servers #2105

Remove explicit dependencies on Shadowsocks from Electron code

• chore(client): pass transport as string in electron, to the extent possible #2142

Remove explicit dependencies on Shadowsocks from Android and Apple code

• chore(client): pass transport as string on Android and Apple #2141
• Apple
  • feat(client): support IPv6 on Apple, pass transport config around as string in Apple code #2132
  • fix(client): properly wait for start to be done #2117
  • refactor(client): delete OutlineLauncher and OutlineTunnelStore #2114
  • refactor(client): clean up Apple VPN code #2113
  • refactor(client): clean up App Groups #2090
  • refactor(client/cordova/apple): assorted cleanups #2071
  • build(client/cordova/apple/ios): upgrade to iOS 13.1 #2057

Create Websocket Stream and Packet Dialers

• feat: create WebSocket Reverse Proxy outline-sdk#202
• feat(x): add Websocket client support outline-sdk#231

Make it possible to change and build the Go code together with the app

• chore(cordova/android): use src/tun2socks, not precompiled third_party version #1816
• chore: add outline-go-tun2socks, except android #1744