Refactor shielded sync

.changelog/unreleased/improvements/3006-refactor-shielded-sync.md

@@ -0,0 +1,9 @@
+This PR refactors shielded sync to make the following improvements
+    * Allow fetching new masp txs and trial-decrypting notes to happen asynchronously
+    * Parallelize the trial-decryptions
+    * Modularize the logic so that we can mock parts of the algorithm for tests and to enable migration over to using a specila masp indexer
+    * Added test coverage
+    * Decouple nullifying notes and updating spent notes from the trial-decryption process
+    * Refactor the masp.rs module in the sdk into several smaller files and submodules
+
+[\#3006](https://github.com/anoma/namada/pull/3006)

crates/apps_lib/src/cli/client.rs

@@ -12,7 +12,7 @@ use crate::cli::cmds::*;
 use crate::client::{rpc, tx, utils};
 
 impl CliApi {
-    pub async fn handle_client_command<C, IO: Io>(
+    pub async fn handle_client_command<C, IO: Io + Send + Sync>(
         client: Option<C>,
         cmd: cli::NamadaClient,
         io: IO,
@@ -323,7 +323,7 @@ impl CliApi {
                             .map(|sk| sk.into())
                             .collect::<Vec<_>>();
                         crate::client::masp::syncing(
-                            chain_ctx.shielded,
+                            &chain_ctx.shielded.utils,
                             &client,
                             &io,
                             args.batch_size,

crates/apps_lib/src/cli/wallet.rs

@@ -16,7 +16,7 @@ use namada::core::address::{Address, DecodeError};
 use namada::core::key::*;
 use namada::core::masp::{ExtendedSpendingKey, MaspValue, PaymentAddress};
 use namada::io::Io;
-use namada_sdk::masp::find_valid_diversifier;
+use namada_sdk::masp::utils::find_valid_diversifier;
 use namada_sdk::wallet::{
     DecryptionError, DerivationPath, DerivationPathError, FindKeyError, Wallet,
 };