[iOS] Language support for external links in privacy section

[moiz994]

Based on the language settings of the user, we need to append a prefix to the URL of the external link mentioned in the agreements file in the config. i.e. if Spanish then insert "es" in the URL.

Spanish: https://www.edx.org/es/webview/edx-privacy-policy/cookies
English: https://www.edx.org/webview/edx-privacy-policy/cookies

We will check if the language is supported or not then proceed to a translated page.
The supported languages are provided in the config under the SUPPORTED_LANGUAGES key.