Use DeviceProtos to get flag file paths

Instead of the hardcoded paths we can use the global constants
for the proto file paths, and get all APEXes with flags from the
same class as well

Bug: 301491148
Test: build + boot
Flag: EXEMPT flagging support change
Change-Id: I685daec3cc1070472157fb40ba30c72a2a80d4b8
diff --git a/Android.bp b/Android.bp
index f8907f3..8e60027 100644
--- a/Android.bp
+++ b/Android.bp
@@ -426,6 +426,7 @@
         "modules-utils-expresslog",
         "perfetto_trace_javastream_protos_jarjar",
         "libaconfig_java_proto_nano",
+        "aconfig_device_paths_java",
     ],
 }