fix(server/v2/cometbft): fix mock store (backport #22293)

[mergify]

Description

Follow-up of #22285

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Author Checklist

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I have...

• included the correct type prefix in the PR title, you can find examples of the prefixes below:

• confirmed ! in the type prefix if API or client breaking change

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• provided a link to the relevant issue or specification

• reviewed "Files changed" and left comments if necessary

• included the necessary unit and integration tests

• added a changelog entry to CHANGELOG.md

• updated the relevant documentation or specification, including comments for documenting Go code

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I have...

• confirmed the correct type prefix in the PR title
• confirmed all author checklist items have been addressed
• reviewed state machine logic, API design and naming, documentation is accurate, tests and test coverage

Summary by CodeRabbit

• New Features

  • Updated the storage mechanism to utilize VersionedWriter, enhancing performance and compatibility.

• Documentation

  • Revised documentation to reflect changes from VersionedDatabase to VersionedWriter across the storage package.

• Bug Fixes

  • Corrected interface assertions and comments to ensure accurate representation of the StorageStore functionality.

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This is an automatic backport of pull request #22293 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of f01baf3 has failed:

On branch mergify/bp/release/v0.52.x/pr-22293
Your branch is up to date with 'origin/release/v0.52.x'.

You are currently cherry-picking commit f01baf302.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   server/v2/cometbft/internal/mock/mock_store.go

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   store/v2/mock/types.go
	deleted by us:   store/v2/storage/README.md
	deleted by us:   store/v2/storage/store.go

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[github-actions]

@mergify[bot] your pull request is missing a changelog!