Disable lockscreen shortcuts when the user enters lockdown mode

When lockdown mode is triggered, disable the lockscreen shortcuts until the user has left lockdown mode

Bug: b/285014861
Test: atest KeyguardQuickAffordanceInteractorTest.kt
Test: manual - while on lockscreen with quick affordance visible, enable lockdown mode. Observe the quick affordance becoming hidden. Unlock device, go back to lockscreen, and observe the quick affordance return.
Change-Id: I7755cf17893e3f98aa66640d68c43bba8bbe7459
Merged-In: I7755cf17893e3f98aa66640d68c43bba8bbe7459