Fix Kimi-K2 tool-call parsing issues (#17376)

Fix Kimi-K2 tool-call parsing issues (#17376)

* Fix kimi-k2 parsing

* fix template & add more tests for kimi-k2

* Another fix for Kimi-K2 chat template.

* enable allow_toolcall_in_think for Kimi-K2

* Refine key-value separator and value end format

* Enable tool call in think for kimi-k2

* allow_toolcall_in_think is now tested with Kimi-K2

* Remove outdated TODO comment in XML tool call parser

Removed TODO comment about untested tool call feature.

* Rename function from "utf8_truncate_safe" to "utf8_truncate_safe_len"