[Android][AdManager][Banner] An ad is not rendered properly. Part 2

[yoalex5]

GitHub issue

1. Multisize support was added
2. UnitTests were added
3. UI test was added

The Utility function looks like:

dfpAdView.setAdListener(new AdListener() {
    @Override
    public void onAdLoaded() {
        super.onAdLoaded();

        Util.findPrebidCreativeSize(dfpAdView, new Util.CreativeSizeCompletionHandler() {
            @Override
            public void onSize(final Util.CreativeSize size) {
                if (size != null) {
                    dfpAdView.setAdSizes(new AdSize(size.getWidth(), size.getHeight()));
                }
            }
        });
    }
});

Please note that Util.CreativeSize size will be always null if API < 19 (Currently the min API for the project is 16)

[yoalex5]

The utility method makes the same as iOS pr

Please do not merge to the master branch
Tomorrow I am going to make full tests on a real device with different AdMAnagerSDK versions.

[yoalex5]

I have updated the PR. Also I have tested it on the real device with different AdManagerSDK versions.

[yoalex5]

@ppuviarasu, Could you please review this PR ?