Undeprecated the unversioned style URL factory methods in MGLStyle for consistency with the Android and Qt SDKs. Added warnings about using them with the runtime styling API.
Refactored mbgl::util::default_styles to track different versions for different styles.
Cherry-picked from 9e384b78fb.
Upgraded from v9 default styles to v10 wherever the developer expects to get the latest and greatest, as well as in a couple tests where it may be beneficial to ensure that we can handle a two-digit version number in the style URL.
Cherry-picked from ed54849e99.