Handle PayloadConfig in Microdroid

Either read the config from JSON or build it from the values in
metadata.

In the latter case, include a hash of the config values in the DICE
config_desc instead of the config path.

Bug: 243513572
Test: atest MicrodroidTests
Change-Id: Ifa1c5dfa17d11a1589621fa265709735d73d4f61
diff --git a/microdroid/payload/metadata.proto b/microdroid/payload/metadata.proto
index 229d03f..06cbbf4 100644
--- a/microdroid/payload/metadata.proto
+++ b/microdroid/payload/metadata.proto
@@ -68,12 +68,8 @@
   // Path to the payload binary file inside the APK.
   string payload_binary_path = 1;
 
-  // Required.
-  // Whether tombstones from crashes inside the VM should be exported to the host.
-  bool export_tombstones = 2;
-
   // Optional.
   // Arguments to be passed to the payload.
   // TODO(b/249064104): Remove this
-  repeated string args = 3;
+  repeated string args = 2;
 }