Fix icon loading in controls

This introduces a SafeIconLoader that uses the safe loading call from
Icon to make sure that the icon can be accessed by the uid of the
current controls app + user.

Test: manual, using POC apk
Test: atest com.android.systemui.controls
Flag: EXEMPT bugfix
Bug: 322818950

Change-Id: I9419a11466545b9373bd3d1f59c81931a81b2939