MINOR: http: use http uri parser for path

MINOR: http: use http uri parser for path

Replace http_get_path by the http_uri_parser API. The new functions is
renamed http_parse_path. Replace duplicated code for scheme and
authority parsing by invocations to http_parse_scheme/authority.

If no scheme is found for an URI detected as an absolute-uri/authority,
consider it to be an authority format : no path will be found. For an
absolute-uri or absolute-path, use the remaining of the string as the
path. A new http_uri_parser state is declared to mark the path parsing
as done.