Security improvements

ExternalSurvey.js

• Parse messages used directly in HTML

SurveyFactory.php

• Validate https for external survey link

ExternalSurvey.php

• Add the link to getMessages

utils.js

• Extract a country code from the GeoIP cookie and return if
  • it is less than 3 characters in length per ISO_3166-1.
  • Otherwise, returns Unknown.

en.json

• Update example external link so it validates

Bug: T110662
Change-Id: I742221107e5becc784b2721b4df070d8cccbffe9