Fix set-status crash inside if/endif at remap time

Operators inside an if/endif block never had set_hook() called on them,
so _hook retained its default value of TS_HTTP_READ_RESPONSE_HDR_HOOK.
When set-status executed at REMAP_PSEUDO_HOOK time, exec() took the
response-hook branch and called TSHttpHdrStatusSet on a request buffer,
corrupting the header union and crashing.

Fix the operator to check TSHttpHdrTypeGet() at runtime instead of
trusting get_hook().  Removed _hook and get_hook() from operators.

set_hook() becomes is_hook_valid() in Statement and RuleSet to
only validate hook compatibility without mutating _hook.

Upgrade the HTTPHdr::status_set/reason_set asserts to release_assert so
that writing response fields into a request buffer is caught immediately
rather than silently corrupting memory.

Includes an autest that reproduces the crash scenario: set-status 403
inside an if/endif block under REMAP_PSEUDO_HOOK.

Author: moonchen

tests/gold_tests/pluginTest/header_rewrite/header_rewrite_bundle.replay.yaml

@@ -176,6 +176,13 @@ autest:
             args:
               - "rules/rule_session_vars.conf"
 
+      - from: "http://www.example.com/from_18/"
+        to: "http://backend.ex:{SERVER_HTTP_PORT}/to_18/"
+        plugins:
+          - name: "header_rewrite.so"
+            args:
+              - "rules/set_status_in_if.conf"
+
     log_validation:
       traffic_out:
         excludes:
@@ -1880,3 +1887,27 @@ sessions:
       headers:
         fields:
         - [ X-Session-Seen, { value: "yes", as: equal } ]
+
+# Test 67: set-status inside if/endif at REMAP_PSEUDO_HOOK time.
+# Before the fix, the set-status operator inside an if/endif block retained
+# its default _hook (TS_HTTP_READ_RESPONSE_HDR_HOOK), so exec() called
+# TSHttpHdrStatusSet on a request buffer, corrupting the union and crashing.
+- transactions:
+  - client-request:
+      method: "GET"
+      version: "1.1"
+      url: /from_18/test
+      headers:
+        fields:
+        - [ Host, www.example.com ]
+        - [ uuid, 67 ]
+
+    server-response:
+      status: 200
+      reason: OK
+      headers:
+        fields:
+        - [ Connection, close ]
+
+    proxy-response:
+      status: 403

tests/gold_tests/pluginTest/header_rewrite/rules/set_status_in_if.conf

@@ -0,0 +1,27 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# Minimal reproduction for set-status inside if/endif at remap time.
+# Before the fix, the operator's _hook defaulted to
+# TS_HTTP_READ_RESPONSE_HDR_HOOK, so exec() called TSHttpHdrStatusSet
+# on a request buffer, corrupting the header union and crashing.
+#
+cond %{REMAP_PSEUDO_HOOK}
+    if
+        cond %{CLIENT-URL:PATH} /from_18/
+            set-status 403
+    endif