Replace http_parser.rb with llhttp or other equivalents

[ashie]

Describe the bug
Fluentd depends on http_parser.rb but it's not maintained and not released new version since December 11, 2013.
In this gem, vulnerability is often detected mistakenly by several security tools because it includes a garbage Gemfile.lock. e.g.) #3409 #3374

I'm troublesome to support such issue, so that I've gotten ownership of http_parser.rb and I'll release a new gem which fixes this issue. Although such false positive will be suppressed by it, we should consider replacing http_parser.rb with other equivalents such as llhttp because dependent http-parser is already dead too.

To Reproduce
See https://github.com/nodejs/http-parser

http-parser is not actively maintained. New projects and projects looking to migrate should consider llhttp.

Expected behavior
Dependent libraries should be well maintained.

Your Environment
N/A

Your Configuration
N/A

Your Error Log
N/A

Additional context
N/A