[refactoring] Group all the CBOR util functions in cbor_util

This cl only moves all the CBOR utility functions in one place.
Some return error types are adjusted to adapt the change. There
should be no behavior change.

Bug: 310931749
Test: atest rialto_test
Change-Id: Ie3db9c93b1355d25d7d796818e19e554560e1f23
diff --git a/libs/bssl/src/evp.rs b/libs/bssl/src/evp.rs
index 86f99a8..fe3d88e 100644
--- a/libs/bssl/src/evp.rs
+++ b/libs/bssl/src/evp.rs
@@ -17,9 +17,7 @@
 use crate::cbb::CbbFixed;
 use crate::digest::{Digester, DigesterContext};
 use crate::ec_key::EcKey;
-use crate::util::{
-    check_int_result, get_label_value, get_label_value_as_bytes, to_call_failed_error,
-};
+use crate::util::{check_int_result, to_call_failed_error};
 use alloc::vec::Vec;
 use bssl_avf_error::{ApiName, Error, Result};
 use bssl_ffi::{
@@ -27,6 +25,7 @@
     EVP_PKEY_new_raw_public_key, EVP_PKEY_set1_EC_KEY, EVP_marshal_public_key, EVP_PKEY,
     EVP_PKEY_ED25519, EVP_PKEY_X25519,
 };
+use cbor_util::{get_label_value, get_label_value_as_bytes};
 use ciborium::Value;
 use core::ptr::{self, NonNull};
 use coset::{