[compass_app] replace `SharedPreferences` with `SharedPreferencesWithCache` (or `SharedPreferencesAsync`)

[rusty-snake]

https://pub.dev/packages/shared_preferences:

Starting with version 2.3.0 there are three available APIs that can be used in this package. [SharedPreferences] is a legacy API that will be deprecated in the future. We highly encourage any new users of the plugin to use the newer [SharedPreferencesAsync] or [SharedPreferencesWithCache] APIs instead.

Consider migrating existing code to one of the new APIs. See below for more information.

[chayan-1906]

Hi! I'm new to open source and would like to work on this issue as my first contribution. I understand this involves migrating from SharedPreferences to SharedPreferencesWithCache/SharedPreferencesAsync in the compass_app.
I've read the migration guide, but haven't started implementation yet. Would it be okay if I take this on? I might need some guidance along the way.

@ericwindmill - could you assign this to me if it's available?