MINOR: h2: pass accept-invalid-http-request down the request parser

MINOR: h2: pass accept-invalid-http-request down the request parser

Origin: https://git.haproxy.org/?p=haproxy-2.6.git;a=commit;h=014945a1508f43e88ac4e89950fa9037e4fb0679

We're adding a new argument "relaxed" to h2_make_htx_request() so that
we can control its level of acceptance of certain invalid requests at
the proxy level with "option accept-invalid-http-request". The goal
will be to add deactivable checks that are still desirable to have by
default. For now no test is subject to it.

(cherry picked from commit d93a00861d714313faa0395ff9e2acb14b0a2fca)
 [ad: backported for following fix : BUG/MINOR: h2: reject more chars
  from the :path pseudo header]
Signed-off-by: Amaury Denoyelle <adenoyelle@haproxy.com>
(cherry picked from commit b6be1a4f858eb6602490c192235114c1a163fef9)
Signed-off-by: Amaury Denoyelle <adenoyelle@haproxy.com>
(cherry picked from commit 26fa3a285df0748fc79e73e552161268b66fb527)
Signed-off-by: Amaury Denoyelle <adenoyelle@haproxy.com>
Gbp-Pq: Name MINOR-h2-pass-accept-invalid-http-request-down-the-r.patch