Get CompOS talking to diced

Create a module in compsvc to handle using DICE for signing. Initially
we just expose a method for returning our key's attestation
chain.

Add a method to composd, accessed via compos_cmd, to exercise this
functionality for testing purposes.

Bug: 214233409
Test: composd_cmd dice
Change-Id: I65ef19d0126862b800b6539ae1798b1a433085b8
diff --git a/compos/Android.bp b/compos/Android.bp
index ab55efb..18fd28f 100644
--- a/compos/Android.bp
+++ b/compos/Android.bp
@@ -6,7 +6,9 @@
     name: "compsvc",
     srcs: ["src/compsvc_main.rs"],
     rustlibs: [
+        "android.hardware.security.dice-V1-rust",
         "android.hardware.security.keymint-V1-rust",
+        "android.security.dice-rust",
         "android.system.keystore2-V1-rust",
         "android.system.virtualmachineservice-rust",
         "authfs_aidl_interface-rust",