Backport to branch(3) : Introduce TransactionContext in Consensus Commit

[feeblefakie]

This is an automated backport of the following:

• Original PR: Introduce TransactionContext in Consensus Commit #3039
• Backported commit: 514d720

Please merge this PR after all checks have passed.

[gemini-code-assist]

Summary of Changes

Hello @feeblefakie, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a new TransactionContext object within the Consensus Commit transaction mechanism. This significant refactoring centralizes all transaction-specific state, which was previously distributed across various components like Snapshot and CrudHandler. The change aims to streamline the transaction management API, making the codebase more modular, easier to understand, and simpler to maintain by consolidating transaction-related data and behavior into a single, cohesive unit.

Highlights

• Introduction of TransactionContext: A new TransactionContext object has been introduced to centralize all transaction-specific state, including the transaction ID, isolation level, read-only status, one-operation status, the transaction snapshot, open scanners, and recovery results. This object is now passed around instead of individual parameters.
• Refactoring of CrudHandler and CommitHandler: The CrudHandler and CommitHandler classes have been refactored to remove transaction-specific state and logic, delegating these responsibilities to the new TransactionContext. Their method signatures have been updated to accept TransactionContext where appropriate, simplifying their APIs.
• Consolidation of Transaction State: Information previously managed separately within Snapshot (like transaction ID, isolation level, and validation requirements) and CrudHandler (like read-only status, one-operation mode, scanners, and recovery results) is now consolidated within TransactionContext.
• Renaming of BeforePreparationHook: The BeforePreparationSnapshotHook interface and its related error message have been renamed to BeforePreparationHook to reflect the broader context now provided by TransactionContext.

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[gemini-code-assist]

Code Review

This pull request is a backport that introduces TransactionContext to encapsulate transaction-specific data. This is a significant and beneficial refactoring that makes CrudHandler and CommitHandler stateless and reusable across transactions, which should reduce object creation overhead. The changes are extensive but appear to be correctly implemented throughout the consensus-commit mechanism.

I have one suggestion regarding the new TransactionContext class to improve its encapsulation and prevent potential misuse, especially from BeforePreparationHook implementations.