Read the algorithm of the leaf public key in DICE chain in pvmfw

The leaf key algorithm will be used to select the authority key
algorithm in the multi-algorithm DICE handover derivation.

Bug: 357008987
Test: atest MicrodroidHostTests
Change-Id: I7cb93167cb97a7831fd26a2ffbf4cff6bc5748e1
diff --git a/guest/pvmfw/src/main.rs b/guest/pvmfw/src/main.rs
index 1e88c4b..aeced51 100644
--- a/guest/pvmfw/src/main.rs
+++ b/guest/pvmfw/src/main.rs
@@ -200,6 +200,8 @@
         Cow::Owned(truncated_bcc_handover)
     };
 
+    trace!("BCC leaf subject public key algorithm: {:?}", bcc.leaf_subject_pubkey().cose_alg);
+
     dice_inputs
         .write_next_bcc(
             new_bcc_handover.as_ref(),