[x509] Parse certificate chain from RKPD into individual certificate

This cl also adjusts the order of the certificates to place the
leaf certificate at the beginning, ensuring consistency with the
certificate order from RKP.

The new test is added to busytown config at cl/584885373.

Bug: 309780089
Test: virtualizationservice_test
Change-Id: Ic3cfdd174483d0905d741c40fef730c652c078c4
diff --git a/TEST_MAPPING b/TEST_MAPPING
index 6983fde..4da96c8 100644
--- a/TEST_MAPPING
+++ b/TEST_MAPPING
@@ -117,6 +117,9 @@
       "path": "packages/modules/Virtualization/service_vm/requests"
     },
     {
+      "path": "packages/modules/Virtualization/virtualizationservice"
+    },
+    {
       "path": "packages/modules/Virtualization/vm"
     },
     {