Distinguish multiple PendingIntents via requestCode

Settings uses a system of intent extras to open subsettings pages. When
PendingIntents are created from these Intents, the system does not think
they are unique as extras are not included in this equality check. So
only one of them is likely to work.

A unique request code can be used to distinguish between them.

Bug: 238605613
Test: atest LockScreenSafetySourceTest
Merged-In: Ia59197eeb86e988d9ffbb86caff4bbda7b30f059
Change-Id: Ia59197eeb86e988d9ffbb86caff4bbda7b30f059
(cherry picked from commit f2b0cedc)