[hex] Use libhex to encode hex string in avmd and apexutil

Bug: 239413416
Test: atest avmdtool_tests libapexutil_rust.test
Change-Id: I58fcc32f62bea1cd34b171ac336a1ed13f5735b8
diff --git a/avmd/Android.bp b/avmd/Android.bp
index 6d91b59..0b87a7b 100644
--- a/avmd/Android.bp
+++ b/avmd/Android.bp
@@ -9,8 +9,8 @@
     srcs: ["src/lib.rs"],
     prefer_rlib: true,
     rustlibs: [
+        "libhex",
         "libserde",
-        "libapexutil_rust", // TODO(b/239413416): Remove this after adding hex
         "libapkverify",
     ],
 }
diff --git a/avmd/src/avmd.rs b/avmd/src/avmd.rs
index 05fc201..cb02f39 100644
--- a/avmd/src/avmd.rs
+++ b/avmd/src/avmd.rs
@@ -18,7 +18,6 @@
     string::{String, ToString},
     vec::Vec,
 };
-use apexutil::to_hex_string;
 use apkverify::SignatureAlgorithmID;
 use core::fmt;
 use serde::{Deserialize, Serialize};
@@ -106,7 +105,7 @@
         writeln!(f, "  VBMeta descriptor:")?;
         writeln!(f, "    namespace:             {}", self.resource.namespace)?;
         writeln!(f, "    name:                  {}", self.resource.name)?;
-        writeln!(f, "    vbmeta digest:         {}", to_hex_string(&self.vbmeta_digest))?;
+        writeln!(f, "    vbmeta digest:         {}", hex::encode(&self.vbmeta_digest))?;
         Ok(())
     }
 }
@@ -132,7 +131,7 @@
         writeln!(f, "    namespace:             {}", self.resource.namespace)?;
         writeln!(f, "    name:                  {}", self.resource.name)?;
         writeln!(f, "    Signing algorithm ID:  {:#04x}", self.signature_algorithm_id.to_u32())?;
-        writeln!(f, "    APK digest:            {}", to_hex_string(&self.apk_digest))?;
+        writeln!(f, "    APK digest:            {}", hex::encode(&self.apk_digest))?;
         Ok(())
     }
 }