Early exit in HTTP Parser if content-length exceeds max_body_size

[achamayou]

See https://github.com/microsoft/scitt-ccf-ledger/issues/247

We would need to add a check in https://github.com/microsoft/CCF/blob/93f3ae44097440a2e3ce55e4bf9537008b91bf99/src/http/http_parser.h#L196 for content-length, and terminate early there. At the moment, this is checked later on, while the body is appended to: https://github.com/microsoft/CCF/blob/93f3ae44097440a2e3ce55e4bf9537008b91bf99/src/http/http_parser.h#L249