Refine benchmarking

[fktn-k]

This PR has refined the benchmarking tool and data files some of which are incorporated from the miroyip/nativejson-benchmark repository.
Also, rapidyaml used there has been updated from 0.6.0 to 0.7.0 which includes huge parser improvements, and rapidyaml usages with mutable buffers have been fixed (I didn't fully understand how it worked at the time I introduced the tool).

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Pull Request Checklist

Read the CONTRIBUTING.md file for detailed information.

• [x] Changes are described in the pull request or in a referenced issue.
• [x] The test suite compiles and runs without any error.
• [x] The code coverage on your branch is 100%.
• [x] The documentation is updated if you added/changed a feature.

Please don't

• The C++11 support varies between different compilers and versions. Please note the list of supported compilers. Some compilers like GCC 4.7 (and earlier), Clang 3.3 (and earlier), or Microsoft Visual Studio 13.0 and earlier are known not to work due to missing or incomplete C++11 support. Please refrain from proposing changes that work around these compiler's limitations with #ifdefs or other means.
• Please refrain from proposing changes that would break YAML specifications. If you propose a conformant extension of YAML to be supported by the library, please motivate this extension.
• Please do not open pull requests that address multiple issues.

[github-actions[bot]]

:octocat: Upload Coverage Event Notification

Coverage data has been uploaded for the commit 90ac1ff7034613b7515fffd58bb0b59015ba6fff. You can download the artifact which contains the same file uploaded to the Coveralls and its HTML version.

Name	fkYAML_coverage.pr397.zip
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