Add nullaway errorprone plugin for nullness check

Bug: 304077181
Test: manual - make Settings RUN_ERROR_PRONE=true
Change-Id: Ic523b966271d8f16bf8b3df5b961c5ffbc17d76c

Android.bp

@@ -123,6 +123,13 @@ android_library {
         "androidx.room_room-compiler-plugin",
     ],
 
+    errorprone: {
+        extra_check_modules: ["//external/nullaway:nullaway_plugin"],
+        javacflags: [
+            "-XepOpt:NullAway:AnnotatedPackages=com.android.settings",
+        ],
+    },
+
     libs: [
         "telephony-common",
         "ims-common",