feat(client): Add oppportunistic upload in parallel to registration (#2748)

* feat(client): Support targeted uploads and cooperative cancellation

* feat(client): Wire upload intent into client code

* feat(client): Add oppportunistic upload in parallel to registration

* rebase

* address review comments

* Address more review comments

* address comments

Author: sadhansood

crates/walrus-e2e-tests/tests/test_client.rs

@@ -378,6 +378,8 @@ async fn test_inconsistency(failed_nodes: &[usize]) -> TestResult {
             TailHandling::Blocking,
             None,
             None,
+            None,
+            None,
         )
         .await?;
 

crates/walrus-sdk/client_config_example.yaml

@@ -45,6 +45,8 @@ communication_config:
     secondary_weight: 0.5
     min_blob_size_bytes: 52428800
   upload_mode: balanced
+  pending_uploads_enabled: false
+  optimistic_upload_max_blob_bytes: 4194304
   registration_delay_millis: 200
   max_total_blob_size: 1073741824
   committee_change_backoff: