Don't set backgroundImageLayout if device is Android 12 or higher

[emawby]

Description

One Line Summary

Don't set backgroundImageLayout if device is Android 12 or higher

Details

Documentation for Android Background Images
We currently add the backgroundImageLayout in the addBackgroundImage method of GenerateNotification.java

We are now checking for the device SDK version being less than 31 (s) and returning early if >= 31.

Motivation

Android 12+ changed the "Customizable Area" within notifications. So background images will look different and we recommend creating your own custom layout to handle this. Therefore we have decided to disable background image layouts for devices on Android 12+.

Scope

Notification appearance for Android 12+ devices only.

Testing

Unit testing

OPTIONAL - Explain unit tests added, if not clear in the code.

Manual testing

RECOMMEND - OPTIONAL - Explain what scenarios were tested and the environment.
Example: Tested opening a notification while the app was foregrounded, app build with Android Studio 2020.3 with a fresh install of the OneSignal example app on a Pixel 6 with Android 12.

Affected code checklist

• Notifications
  • Display
  • Open
  • Push Processing
  • Confirm Deliveries
• Outcomes
• Sessions
• In-App Messaging
• REST API requests
• Public API changes

Checklist

Overview

• I have filled out all REQUIRED sections above
• PR does one thing
  • If it is hard to explain how any codes changes are related to each other then it most likely needs to be more than one PR
• Any Public API changes are explained in the PR details and conform to existing APIs

Testing

• I have included test coverage for these changes, or explained why they are not needed
• All automated tests pass, or I explained why that is not possible
• I have personally tested this on my device, or explained why that is not possible

Final pass

• Code is as readable as possible.
  • Simplify with less code, followed by splitting up code into well named functions and variables, followed by adding comments to the code.
• I have reviewed this PR myself, ensuring it meets each checklist item
  • WIP (Work In Progress) is ok, but explain what is still in progress and what you would like feedback on. Start the PR title with "WIP" to indicate this.

---

This change is 

[jkasten2]

PR looks good to me.

Tests failed but looks to be due to a flaky one, I kicked off another run.

Reviewed 3 of 3 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @emawby)