[execution-pool] Create iterator on TransactionShuffler

[hariria]

Description

Context

The TransactionShuffler trait defines a customizable strategy for shuffling transactions to minimize sequential execution and promote parallelism in transaction processing. Previously the shuffler type was hard-coded in the execution pipeline as a UseCaseAwareShuffler.

Objective

The goal of this PR was two-fold:

1. In our execution pipeline, specifically the execute_stage function, create a TransactionShufflerIterator that works with any TransactionShuffler provided in the ExecuteBlockCommand. As mentioned above, this was previously hard-coded to use a UseCaseAwareTransactionShuffler. Part of this work included extending the TransactionShuffler trait to include two new functions:
   • signed_transaction_iterator
   • signature_verified_transaction_iterator
2. Introduce a ShuffledTransactionIterator that works on SenderAwareTransaction, a new trait that mimics functionality found in UseCaseAwareTransaction.

Additional work was done to refactor the SenderAwareShuffler to more closely resemble the UseCaseAwareShuffler for consistency.

How Has This Been Tested?

• [✅ Passing] All pre-existing SenderAwareShuffler unit tests.
• [✅ Passing] Lints.
• [❌ Failing] Tests that were already failing in brian/exec-window-exec-optimize-2, i.e.,
  • quorum_store::tests::batch_proof_queue_test::test_proof_pull_proofs_with_duplicates
  • round_manager::round_manager_test::commit_pipeline_test

cargo test --package aptos-consensus --lib transaction_shuffler::sender_aware::tests

[trunk-io]

⏱️ 59m total CI duration on this PR

Job	Cumulative Duration	Recent Runs
rust-move-tests	13m	🟩
rust-cargo-deny	9m	🟩 🟩 🟩 🟩 🟩
rust-move-tests	7m	🟥
rust-move-tests	7m	🟥
rust-move-tests	7m	🟥
rust-move-tests	5m	⬜
check-dynamic-deps	5m	🟩 🟩 🟩 🟩 🟩
general-lints	2m	🟩 🟩 🟩 🟩 🟩
semgrep/ci	2m	🟩 🟩 🟩 🟩 🟩
file_change_determinator	53s	🟩 🟩 🟩 🟩 🟩
permission-check	11s	🟩 🟩 🟩 🟩 🟩
permission-check	11s	🟩 🟩 🟩 🟩 🟩

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