[BFT] Requester Engine update to follow guidelines

[durkmurder]

Context

This PR updates Requester Engine to the latest guidelines we are using for BFT Engines.

What was done:

• Engine now implements MessageProcessor interface.
• Engine now uses fixed-bound queues for inbound messages.
• Engine now relines on the ComponentManager to implement a restartable component.

I have decided to keep logic as it is to prevent changes to the actual business logic to reduce surface of changes and to keep the existing working code as it is.

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None

[codecov-commenter]

Codecov Report

❌ Patch coverage is 16.93548% with 103 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
engine/common/requester/engine.go	22.58%	71 Missing and 1 partial ⚠️
engine/testutil/nodes.go	0.00%	13 Missing ⚠️
engine/fifoqueue.go	0.00%	5 Missing ⚠️
cmd/access/node_builder/access_node_builder.go	0.00%	4 Missing ⚠️
cmd/consensus/main.go	0.00%	4 Missing ⚠️
cmd/execution_builder.go	0.00%	4 Missing ⚠️
engine/testutil/mock/nodes.go	0.00%	1 Missing ⚠️

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