add a option to override domain used to query https record

[rhjdvsgsgks]

cloudflare still didnt provide option to enable ech on free account. however if taking echConfig from other domain which have ech in https record would just make ech works on your domain. because they are all using cloudflare-ech.com for outer ClientHello.

this pr added a option to override the domain used to query for echConfig. that means i dont need to update echConfig manually everytime ttl exceed.

{
  "log": {
    "error": {
      "level": "Debug",
      "type": "Console"
    },
    "access": {
      "type": "None"
    }
  },
  "outbounds": [
    {
      "protocol": "vmess",
      "settings": {
        "address": "cf.ip",
        "port": 443,
        "uuid": "id"
      },
      "streamSettings": {
        "transport": "httpupgrade",
        "transportSettings": {
          "host": "any.cf.domain",
          "path": "path"
        },
        "security": "tls",
        "securitySettings": {
          "serverName": "any.cf.domain",
          "echDOHserver": "dohserver",
          "echQueryDomain": "cloudflare-ech.com",
          "nextProtocol": [
            "http/1.1"
          ]
        }
      }
    }
  ],
  "inbounds": [
    {
      "protocol": "socks",
      "settings": {
        "udpEnabled": false,
        "address": "127.0.0.1",
        "packetEncoding": "Packet"
      },
      "port": 17794,
      "listen": "127.0.0.1"
    }
  ]
}

protoc version been bumped to make vprotogen able to run on my env. rebase to delete them if you want

[xiaokangwang]

Thanks for your contribution. Your commit history might be edited upon merging as there was too many unrelated changes.

[xiaokangwang]

Thanks for your contribution. This merge request will be merged with its history adjusted.