This is a temporary change to update the default app icon to Spectrum. It make the following changes:

• Adds blue (the normal default) as a proper custom icon, selectable in the App Icon settings screen. This is done by providing some extra icon files and adding entries to the Info.plist files. This will allow users to switch back to blue if they'd like to.
• Adds a new AppIconSpectrum entry to the main asset catalog and updates the Info.plists and build settings to reference this new app icon as the default. Any user without a custom icon should be updated to this new icon.
• Makes a small tweak to the AppIconViewController so that Spectrum is treated as the default and sorted to the top of the list.

To test

I can think of a number of situations to test:

No existing custom icon

• Build and run an existing build of the app (I guess release/17.5). Do not select a custom icon.
• Build and run this branch over the top, and you should see the app icon gets updated to Spectrum.
• Visit the Me > App Settings > App Icon settings and ensure that spectrum is checked at the top and you can choose an alternative (including Blue).

Existing custom icon

• Follow the steps above, but before installing this branch, set a custom icon to something else. Ensure that setting is respected when upgrading.

Reverting

• Follow the steps in the no existing custom icon test, and don't choose a custom icon.
• After installing these changes and running, build and run 17.5 again over the top.
• The icon should revert back to blue and if you check the AppIconViewController, it should reflect that choice at the top of the list.

Reverting after switching back to blue

• Follow the steps in the no existing custom icon test, and then manually switch your icon back to blue in the app settings..
• Build and run 17.5 again over the top.
• I'm hoping that the icon should revert back to blue and if you check the AppIconViewController, it should reflect that choice at the top of the list. I haven't had chance to check this yet.

Regression Notes

1. Potential unintended areas of impact

This should only affect app icons.

2. What I did to test those areas of impact (or what existing automated tests I relied on)
3. What automated tests I added (or what prevented me from doing so)

N / A

PR submission checklist:

• I have completed the Regression Notes.
• I have considered adding unit tests for my changes.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.