header_rewrite: Improve URL Error messages

[bneradt]

Old log:
ERROR: [header_rewrite] Rule not supported at this hook

New log:
ERROR: [header_rewrite] Rule not supported at hook=TS_HTTP_READ_RESPONSE_HDR_HOOK: %{TO-URL:URL} in /tmp/sb/header_rewrite_unsupported_url_hook/unsupported_url_hook.conf:18

[Copilot]

Pull request overview

This PR improves diagnostics from the header_rewrite plugin by enriching ConditionUrl runtime error logs with the executing hook, the specific URL token involved, and (when available) the originating config file and line number. This helps operators quickly locate and fix unsupported URL usages at particular hooks.

Changes:

• Track and propagate config file/line information through Statement and Value so nested %{...} expansions can report their origin.
• Record the active TSHttpHookID in Resources during gather() so runtime URL failures can include the hook context.
• Add a ConditionUrl::log_error() helper and use it for URL retrieval / unsupported-hook errors with improved message formatting.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
plugins/header_rewrite/value.cc	Propagates config location from the owning Statement into Value and any %{...} conditions created from the value string.
plugins/header_rewrite/statement.h	Adds config filename/line storage and accessors to the Statement base class.
plugins/header_rewrite/ruleset.cc	Sets config location on created operators/conditions based on parser filename/line.
plugins/header_rewrite/resources.h	Adds a hook field to Resources to retain the active hook for error reporting.
plugins/header_rewrite/resources.cc	Stores the active hook into Resources::hook at the start of gather().
plugins/header_rewrite/operators.cc	Sets config location on operators/conditions created within OperatorIf.
plugins/header_rewrite/conditions.h	Declares ConditionUrl::log_error() helper.
plugins/header_rewrite/conditions.cc	Implements hook/URL-type naming helpers and uses log_error() for improved URL-related runtime error messages.