[execution-pool] BlockRetrievalRequest struct -> enum

[hariria]

Description

Deprecates the BlockRetrievalRequest struct in favor of a BlockRetrievalRequest enum. This is needed as execution pool plans to make BlockRetrievalRequests that include epoch and round information instead of target_block_id.

The plan is to phase this in two releases. The first release will introduce the new BlockRetrievalRequest enum and all corresponding structs / logic that use it. The second release will deprecate the BlockRetrievalRequestV1 struct and all related structs / logic.

Important

Some TODOs around deprecation are already marked in the code. Additional TODO in future PRs:

• process_block_retrieval param should change to IncomingBlockRetrievalRequestV2
• spawn_block_retrieval_task channel should change to IncomingBlockRetrievalRequestV2

Additional Questions

• Why does consensus.yaml require TUPLEARRAY instead of TUPLE?

How Has This Been Tested?

[trunk-io]

⏱️ 20m total CI duration on this PR

Job	Cumulative Duration	Recent Runs
check-dynamic-deps	8m	🟩 🟩 🟩 🟩
rust-cargo-deny	7m	🟩 🟩 🟩 🟩
general-lints	2m	🟩 🟩 🟩 🟩
semgrep/ci	2m	🟩 🟩 🟩 🟩
file_change_determinator	42s	🟩 🟩 🟩 🟩
permission-check	7s	🟩 🟩 🟩 🟩
permission-check	7s	🟩 🟩 🟩 🟩

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