Init support userver with honggfuzz

[pavkir]

Added support for the userver web asynchronous framework. I used only honggfuzz engine because it's pretty hard to write a fuzz test for another engine, should to patch a lot of in framework.

This framework dont use any custom parsers, under the hood it used llhttp as http req parser, rapidjson for json processing. Therefore, I used hungfuzz to cover all the functionality, rather than just some of the individual functions/parsers that are already covered by oss-fuzz

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[github-actions]

pavkir is integrating a new project:
- Main repo: https://github.com/userver-framework/userver.git
- Criticality score: 0.55404

[DavidKorczynski]

Are you a maintainer of the project? If not, please do coordinate this with maintainers. It would also be preferred to have fuzzing harnesses upstream if possible.

[pavkir]

Are you a maintainer of the project? If not, please do coordinate this with maintainers. It would also be preferred to have fuzzing harnesses upstream if possible.

Hi, thanks for your reply. No, I'm not the maintainer of this project, just an active user. And I support active communication with the maintainer. cc, @apolukhin - the main maintainer of this project. In the primary_contact field I set Anton's email.

[apolukhin]

I support active communication with the maintainer. cc, @apolukhin - the main maintainer of this project

I confirm that I'm the maintainer of the userver project and confirm that https://github.com/pavkir helps me here