chat : nemotron thinking & toolcalling support (#15676)

* feat: nemotron thinking & toolcalling support

* Trailing whitespaces

* Corrected template for Nemotron

* Template and parser fixes

* Final template and grammar changes

* Whitespace

* Always do lazy grammar processing since </think> tag will always be there.

* Allow extra content after toolcall

* Whitespace

* New tests: thinking + tools, tools + content, thinking + tools + content (new!)

* Whitespace

* Remove cURL test script