Migrate PackageInstaller to androidx.

Test: make PackageInstaller
Bug: 76692459
Change-Id: I8c0bf6768e7bbfc38ec6867c6e0a8bc2cd998551
diff --git a/PermissionController/proguard.flags b/PermissionController/proguard.flags
index 115958f..46a929e 100644
--- a/PermissionController/proguard.flags
+++ b/PermissionController/proguard.flags
@@ -2,7 +2,7 @@
 # Don't warn about those in case this app is linking against an older
 # platform version.  We know about them, and they are safe.
 
--keep class android.support.v7.preference.Preference* {
+-keep class androidx.preference.Preference* {
     *;
 }
--dontwarn android.support.v4.**
+-dontwarn androidx.core.**