Parser and genertal compliance fixes

[marty1885]

In light of current wave of AI based vulns. This PR introduces several fixes into the core framework, unfortunately may impact performance

• Replace sto* with utils::fromString - sto* does not always cleanly parse integers according to RFC (ex. 123x will be parsed by atoi as 123)
• Fix HttpClient leaking if connection breaks mid request
• Validate incoming headers does not contain stray \r or \n or NUL (according to RFC)
• Make sure supplied port numbers are withing uint16 limits and error if not
• Validate the claimed content length in request == number of bytes we got
• Limit the total size of headers (previously not limited)