create In App Message View
open override fun createInAppMessageView(activity: Activity, inAppMessage: IInAppMessage): InAppMessageModalView
This method should either inflate or programmatically create a new View that will be used to display an in-app message. A new View must be created on every call. This prevents the memory leak that would occur if the View was shared by multiple Activity classes.
Note: Do not add click/touch listeners directly to the view. They will be ignored. Instead, use an []IInAppMessageManagerListener] to perform custom logic in response to user action.
Return
View that will be used to display the in-app message.