recursively append properties from super-env in test-settings

[gravityvi]

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[gravityvi]

Example of the feature:

test_setting: {

 browserstack: {
        desiredCapabilities: {
          'bstack:options': {
            local: 'false'
          }
        },
 }

 'browserstack.chrome': {
        extends: 'browserstack',
        desiredCapabilities: {
          browserName: 'chrome',
          chromeOptions: {
            w3c: false
          }
        }
 },
 
 'browserstack.chrome_mac': {
        extends: 'browserstack.chrome',
        desiredCapabilities: {
          os: 'OS X'
        }
  }
}

TEST_ENV='browserstack.chrome_mac'
OUTPUT:

test_setting:{
 'browserstack.chrome_mac': {
        desiredCapabilities: {
          os: 'OS X',
          browserName: 'chrome',
          chromeOptions: {
            w3c: false
          },
          'bstack:options': {
            local: 'false'
          }
        }
  }

 }

}