common/grammar : replace problematic backtracking regex `[\s\S]*` (#18342)

common/grammar : replace problematic backtracking regex `[\s\S]*` (#18342)

* grammar : add support for std::regex_search() with trigger patterns

* common : update hermes2 pro trigger to search instead of match

* common : use regex_search with anchoring for partial matching

* common : adjust regex partial tests to use new pattern

* grammar : check pattern directly instead of adding a type

* common : adjust existing patterns to match new semantics