Add Kotlin intrinsics proguard rules to SystemUI

Introduce several Kotlin Proguard rules to strip synthetically generated
calls to kotlin Intrinsics, particularly for null checks. These checks
are typically inserted at the boundaries between Kotlin and Java, but
add a non-trivial amount to SystemUI code size (~3% of compiled size).

Note that this may change the exception/crash stacks for various crash
clusters, but this Proguard configuration is used in production by a
number of widely distributed apps.

Test: m + boot test
Bug: 203472868
Change-Id: I8547600e28ce026a3fbf6a694192fa3e02b2e630