OMS: Add config_signature policy handling

Alongside SIGNATURE and ACTOR_SIGNATURE policies, add CONFIG_SIGNATURE
policy to overlayable that overlay fulfills if it is signed with the
same certificate as the reference package whose package name is
declared in 'config-signature' tag of SystemConfig and is vetted by
OMS that it's a system pre-installed package.

BUG: 158726924
TEST: regular aapt2, idmap2, OMS tests

Change-Id: I645ee72271496008742886274be0d63a2985201b
diff --git a/cmds/idmap2/tests/TestConstants.h b/cmds/idmap2/tests/TestConstants.h
index 74ea18f..9641f6b5 100644
--- a/cmds/idmap2/tests/TestConstants.h
+++ b/cmds/idmap2/tests/TestConstants.h
@@ -19,11 +19,11 @@
 
 namespace android::idmap2::TestConstants {
 
-constexpr const auto TARGET_CRC = 0x41c60c8c;
-constexpr const auto TARGET_CRC_STRING = "41c60c8c";
+constexpr const auto TARGET_CRC =  0x7c2d4719;
+constexpr const auto TARGET_CRC_STRING = "7c2d4719";
 
-constexpr const auto OVERLAY_CRC = 0xc054fb26;
-constexpr const auto OVERLAY_CRC_STRING = "c054fb26";
+constexpr const auto OVERLAY_CRC = 0x5afff726;
+constexpr const auto OVERLAY_CRC_STRING = "5afff726";
 
 }  // namespace android::idmap2::TestConstants