examples: add the Benchmark tool for TiKV

[LykxSassinator]

Description

This pull request introduces a benchmark tool designed to evaluate the performance of a specific TiKV cluster without the necessity of deploying TiDB.
The motivation of this pr derives from the challenges associated with performance testing TiKV clusters, which typically require deploying one or more TiDB nodes. This process can be time-consuming, and issues related to performance regressions may not be promptly communicated to developers.

Therefore, this pull request offers a simplified implementation of the benchmark tool to address these concerns.

Attention

If you have any other suggestions or proposals regarding this tool, pls comment it. Welcome any advices.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please ask for approval from lykxsassinator, ensuring that each of them provides their approval before proceeding. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[ekexium]

Is a go.sum missing? Do we need tests for this tool? We may also need a manual or readme for it.
I think it is not the best option to put the tool in examples, maybe we can have a bin or tools directory for its, or even a standalone repo.

[LykxSassinator]

Is a go.sum missing? Do we need tests for this tool? We may also need a manual or readme for it. I think it is not the best option to put the tool in examples, maybe we can have a bin or tools directory for its, or even a standalone repo.

FYI, the reason why this tool is set under examples is used to make this tool accessible and easy to use, where the README.md is already specified.

And as for tests, the basic and offline tests have been done for it, which can be reviewed in https://pingcap-cn.feishu.cn/wiki/QtoIwKWqNiiYp7kTujIcjw4RnEh.

Meanwhile, it's acceptable to move this tool into an individual repo if we can make an agreement about this advice.