feature: add transaction getter to validation-tool

[sebtomba]

Description

1. Enhance the validation tool by adding a feature to fetch transactions (up to the chain tip) from a validator node's REST API and store them in a (bcs) file. Note that the tool only saves user-signed transactions.
2. Create a transaction comparison tool that reads stored transactions from the file, requests the corresponding transactions from a remote node, and compares them.

Also, refactor the api command to a subcommand so that every tool can be run independently.

How Has This Been Tested?

1. Run a local validator node on real-world data (e.g. synced from mainnet). Use the waypoint.txt file for the ledger version.
2. Run the tool with the waypoint ledger version - 1000 (or some other number).

./target/debug/validation-tool api transactions --url http://0.0.0.0:8080 --start 19332568 --out ~/tmp/transactions.bin

3. Compare the saved transactions with transactions on a remote validator node.

./target/debug/validation-tool api compare-transactions --url http://0.0.0.0:8080  --in ~/tmp/transactions.bin

Caution

I haven't tested the transaction comparison against one of our mainnet nodes yet.
However, such a test could face issues with Cloudflare's rate limiting.

Key Areas to Review

Type of Change

• New feature
• Bug fix
• Breaking change
• Performance improvement
• Refactoring
• Dependency update
• Documentation update
• Tests

Which Components or Systems Does This Change Impact?

• Validator Node
• Full Node (API, Indexer, etc.)
• Move/Aptos Virtual Machine
• Aptos Framework
• Aptos CLI/SDK
• Developer Infrastructure
• Move Compiler
• Other (specify)

Checklist

• I have read and followed the CONTRIBUTING doc
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I identified and added all stakeholders and component owners affected by this change as reviewers
• I tested both happy and unhappy path of the functionality
• I have made corresponding changes to the documentation

[musitdev]

As you use lines to read the file, perhaps you should use writeln! macro to avoid managing the \n ?

[sebtomba]

I'm using tokio for the async interface, and unfortunately, no writeln! macro is available.

[0xmovses]

What's the status of this PR, there are some conflicts before it can merge.

[sebtomba]

As discussed today, we need to check which parts of this PR are still required. We now want a tool that reads new transactions from the da-sequencer and replays them on the validator node.