Bring back medium rectangle ad size

[chuchuva]

RECTANGLE_HEIGHT_250 for Android is available according to official Meta documentation:

https://developers.facebook.com/docs/audience-network/setting-up/ad-setup/android/banner

It is kFBAdSizeHeight250Rectangle for iOS:

https://developers.facebook.com/docs/audience-network/setting-up/ad-setup/ios/banner

This format is best suited for scrollable feeds or end-of-level screens
This format is highly recommended because it provides higher performance, higher quality, and more CPU efficient

[chungtvdev]

Hi, This Git still work ?