jinja : add missing 'in' test to template engine (#19004) (#19239)

jinja : add missing 'in' test to template engine (#19004) (#19239)

* jinja : add missing 'in' test to template engine (#19004)

The jinja template parser was missing the 'in' test from
global_builtins(), causing templates using reject("in", ...),
select("in", ...), or 'x is in(y)' to fail with
"selectattr: unknown test 'in'".

This broke tool-calling for Qwen3-Coder and any other model
whose chat template uses the 'in' test.

Added test_is_in supporting array, string, and object containment
checks, mirroring the existing 'in' operator logic in runtime.cpp.

Includes test cases for all three containment types plus
reject/select filter usage.

Co-Authored-By: Claude Opus 4.5 <redacted>
* reuse test_is_in in binary op

---------

Co-authored-by: Sid Mohan <redacted>
Co-authored-by: Claude Opus 4.5 <redacted>
Co-authored-by: Xuan Son Nguyen <redacted>