Support devtools and custom profile directory for Chrome via environment variable

[matthewlowry]

Offers a solution for #627.

With this change you can set BROWSER_PROFILE_DIR in the container environment and the devtools proxy process will use that location when looking for the browser profile. E.g.:

{
  "capabilities": {
    "alwaysMatch": {
      "browserName": "chrome",
      "browserVersion": "114.0",
      "goog:chromeOptions": {
        "args": [ "user-data-dir=/profiles/custom.XYZ" ]
      },
      "selenoid:options": {
        "env": [ "BROWSER_PROFILE_DIR=/profiles/custom.XYZ" ]
      }
    }
  }
}

[vania-pooh]

@matthewlowry thank you for contribution!