Add back push_method_enabled enforcement (#9787)

proxy.config.http.push_method_enabled. This adds back the enforcemenent
of this configuration so that hosts can only PUSH when
proxy.config.http.push_method_enabled is 1.

Conflicts:
      proxy/http/HttpSM.cc
      tests/gold_tests/bigobj/bigobj.test.py
      tests/gold_tests/ip_allow/ip_allow.test.py
      tests/gold_tests/proxy_protocol/proxy_serve_stale.test.py
      tests/gold_tests/proxy_protocol/proxy_serve_stale_dns_fail.test.py
1 file changed