[firebase_admob] Banner Ad Horizontal Positioning

[malsabbagh]

Adding the ability to horizontally adjust the ads banner location by specifying an offset from the centre.

Description

• This PR allows the user of firebase_admob to specify an offset in pixels from the horizontal centre of the banner using

• horizontalCenterOffset

The current behaviour allows the user only to specify an anchor top or bottom with an offset from the anchor. But it doesn't allow an offset from the horizontal centre. This PR will add that ability.

The motivation behind the change is to support split screen layout for tablets where ads banner could reside on one side of the screen.

Checklist

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Breaking Change

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• Yes, this is a breaking change (please indicate a breaking change in CHANGELOG.md and increment major revision).
• No, this is not a breaking change.

[malsabbagh]

Hey @amirh & @bparrishMines,

Do you think this would be merged or there are plans that would affect this behaviour to prevent it from being merged in the future? It will be nice to have this as part of the next firebase_admob update.

Thanks,

[bparrishMines]

LGTM

Thanks for the contribution!