Refactor Http1::ChunkedCodingParser to Http1::Parser API with SBuf

Refactor Http1::ChunkedCodingParser to Http1::Parser API with SBuf

* refactor the parse to accept SBuf input buffer using the Parser API
 and shift the MemBuf output buffer accesses to a separate API method.

* refactor the parsing steps to use Parser methods where available and
 Tokenizer for lexical tokenising.

This removes one temporary data copy and two performance regressions
from each chunked message payload processing action. It also removes
c-string operations and strign termination dependency from chunk parsing.