Add COW version to the update_metadata.proto

COW versioning will be used to detect if the COW library
version matches with the version in the proto file.
If not, VABC is disabled.

Bug: 183863613
Test: Apply OTA and verifiy if VABC is disabled if the versioning
doesn't match
Signed-off-by: Akilesh Kailash <akailash@google.com>
Change-Id: I2d8690bd30d3436c6eb281d3e8d6545cb4888a75
diff --git a/update_metadata.proto b/update_metadata.proto
index bc9e34a..93e4e2e 100644
--- a/update_metadata.proto
+++ b/update_metadata.proto
@@ -359,6 +359,10 @@
   // See system/core/fs_mgr/libsnapshot/cow_writer.cpp for available options,
   // as this parameter is ultimated forwarded to libsnapshot's CowWriter
   optional string vabc_compression_param = 4;
+
+  // COW version used by VABC. The represents the major version in the COW
+  // header
+  optional uint32 cow_version = 5;
 }
 
 // Definition has been duplicated from