cbor: allow user to control nesting (#329)

* cbor: allow user to control nesting

 - Make the default read/write entrypoints allow infinite nesting.
 - Add {read,write}_nested() entrypoints that allow the crate user to
   control the depth of nesting that's allowed.
 - Along the way, convert the write[_nested] variants to return a
   `Result<(), EncoderError>` rather than a bool.  This exposes
   more failure information (and forces the caller to take notice
   of those tailures), and allows use of the ? operator.

* fixup: transmute error

Co-authored-by: kaczmarczyck <43844792+kaczmarczyck@users.noreply.github.com>

src/ctap/config_command.rs

@@ -20,7 +20,6 @@ use super::response::ResponseData;
 use super::status_code::Ctap2StatusCode;
 use super::storage::PersistentStore;
 use alloc::vec;
-use sk_cbor as cbor;
 
 /// Processes the subcommand enableEnterpriseAttestation for AuthenticatorConfig.
 fn process_enable_enterprise_attestation(
@@ -100,9 +99,7 @@ pub fn process_config(
         let mut config_data = vec![0xFF; 32];
         config_data.extend(&[0x0D, sub_command as u8]);
         if let Some(sub_command_params) = sub_command_params.clone() {
-            if !cbor::write(sub_command_params.into(), &mut config_data) {
-                return Err(Ctap2StatusCode::CTAP2_ERR_VENDOR_INTERNAL_ERROR);
-            }
+            super::cbor_write(sub_command_params.into(), &mut config_data)?;
         }
         client_pin.verify_pin_uv_auth_token(
             &config_data,