apkdmverity: use data_model crate for better handling of C structs

The data_model:DataInit trait provides methods for converting between
a C struct and an array of the same size, allowing us to drop the hand
crafted as_u8_slice methods.

Bug: N/A
Test: cargo test
Test: atest apkdmverity.test
Change-Id: Iaff910f0a638e91a428777b94dc6fb0b5fe53831
diff --git a/apkverity/Cargo.toml b/apkverity/Cargo.toml
index 43100e5..c367587 100644
--- a/apkverity/Cargo.toml
+++ b/apkverity/Cargo.toml
@@ -14,6 +14,7 @@
 num-derive = "0.3"
 num-traits = "0.2"
 uuid = { version = "0.8", features = ["v1"] }
+data_model = "0.1"
 
 [dev-dependencies]
 tempfile = "3.2"