REORG: h2: extract cookies concat function in http_htx

As specified by RFC 7540, multiple cookie headers are merged in a single
entry before passing it to a HTTP/1.1 connection. This step is
implemented during headers parsing in h2 module.

Extract this code in the generic http_htx module. This will allow to
reuse it quickly for HTTP/3 implementation which has the same
requirement for cookie headers.
3 files changed