[client-vm] Build client VM CSR and sign the CSR with two keys

This cl builds the CSR that a client VM sends to the RKP VM for
remote attestation and adjusted the API accordingly as discussed
in the doc go/pvm-remote-attestation

The CSR payload is signed with both the CDI_Leaf_Priv of the
client VM's DICE chain and the attestation key. RKP VM should
verify the signature later with the CDI_Leaf_Pub extracted
from the same DICE chain in the CSR and the attestation public
key.

The new unit tests are added to config at cl/577763874.

Bug: 303807447
Test: run ServiceVmClientTestApp
Test: atest libservice_vm_comm.test
Test: atest microdroid_manager_test
Change-Id: Ic2c09e7339d9981edda028e2694fa551c911a274
diff --git a/service_vm/comm/TEST_MAPPING b/service_vm/comm/TEST_MAPPING
new file mode 100644
index 0000000..e677ba2
--- /dev/null
+++ b/service_vm/comm/TEST_MAPPING
@@ -0,0 +1,12 @@
+// When adding or removing tests here, don't forget to amend _all_modules list in
+// wireless/android/busytown/ath_config/configs/prod/avf/tests.gcl
+{
+  "avf-presubmit" : [
+    {
+      "name" : "libservice_vm_comm.test"
+    },
+    {
+      "name" : "libservice_vm_comm_nostd.test"
+    }
+  ]
+}
\ No newline at end of file