[cpp-httplib]Add to oss-fuzz

[omjego]

• Depends on Add cpp-httplib to oss-fuzz cpp-httplib#2.
• Will change repo link in Dockerfile after above gets merged.

Testing locally:

cd oss-fuzz
export PROJECT_NAME=cpp-httplib  
python infra/helper.py build_fuzzers --sanitizer address $PROJECT_NAME
python infra/helper.py run_fuzzer $PROJECT_NAME server_fuzzer