[service-vm] Deserialize CBOR-encoded CSR byte array into struct

This CL deserializes the CBOR-encoded CSR provided as a param for
VM attestation into a `Csr` struct.

It also extracts the CSR/attestation key generation function from
microdroid into a standalone library so that we can reuse it in
e2e tests.

The new test target has been added to the busytown config at
cl/581170242.

Test: atest rialto_test
Bug: 309440321
Change-Id: Idbfadd0418822bdf46d6764b9db484f4865aa267
diff --git a/rialto/Android.bp b/rialto/Android.bp
index 326f6fc..28c261e 100644
--- a/rialto/Android.bp
+++ b/rialto/Android.bp
@@ -109,6 +109,8 @@
         "libandroid_logger",
         "libanyhow",
         "libciborium",
+        "libclient_vm_csr",
+        "libdiced_sample_inputs",
         "liblibc",
         "liblog_rust",
         "libservice_vm_comm",