Marcello Câmara

I saw that this is implemented on all the examples folders: ```XML ``` 1) AppOpen: https://github.com/googleads/googleads-mobile-flutter/pull/1172/files#diff-ce2cacda361f60f008608daec0de85463f9c41d2b6ed8279242ff65b0b27c099 2) Banner: https://github.com/googleads/googleads-mobile-flutter/pull/1172/files#diff-065422729ac6c9b5950ec50e23c96293adb847f5b1317ba0f807a9ee4a14e07d 3) Interstitial: https://github.com/googleads/googleads-mobile-flutter/pull/1172/files#diff-edfadc71f4943e251704336e4e4c3e685c0844261a37ac8aa08b86be13345948 4) Mediation: https://github.com/googleads/googleads-mobile-flutter/pull/1172/files#diff-e56b43ee67852aaeb05046321fcebb7f988ebbe61d71812caa9f5f786fcbbaf9 5, 6, 7 e 8...