Add block building simulator tool

[dmitriy-b]

Changes

Added Engine API Proxy - a new diagnostic/testing tool located at tools/EngineApiProxy. It sits between Consensus Layer (CL) and Execution Layer (EL) clients to intercept and validate Engine API messages to ensure execution clients can build valid blocks and catch validation issues early.

The tool does not modify the Nethermind codebase and has its own dependency management (tools/EngineApiProxy/Directory.Packages.props), but relies on some core Nethermind libraries.

Types of changes

What types of changes does your code introduce?

• Bugfix (a non-breaking change that fixes an issue)
• New feature (a non-breaking change that adds functionality)
• Breaking change (a change that causes existing functionality not to work as expected)
• Optimization
• Refactoring
• Documentation update
• Build-related changes
• Other: Description

Testing

Requires testing

• Yes
• No

If yes, did you write tests?

• Yes
• No

Documentation

Requires documentation update

• Yes
• No

Requires explanation in Release Notes

• Yes
• No

Remarks

Tested together with @kamilchodola

[kamilchodola]

One problem with build but just set it up on mainnet node and works amazing.