feat(auth): adding support for keychain sharing using app groups #465

Job	Run time
Build Amplify Swift for watchOS / Build Amplify-Build \| watchOS	9m 29s
Build Amplify Swift for iOS / Build Amplify-Build \| iOS	8m 51s
Build Amplify Swift for macOS / Build Amplify-Build \| macOS	5m 27s
Build Amplify Swift for tvOS / Build Amplify-Build \| tvOS	7m 4s
Confirm Passing Build Steps	1s
	30m 52s

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