[C++] Complete std::numeric_limits<Float16> specialization #49123
Description
Describe the enhancement requested
https://github.com/apache/arrow/blob/main/cpp/src/arrow/util/float16.h#L188
Component(s)
C++
{{ message }}
https://github.com/apache/arrow/blob/main/cpp/src/arrow/util/float16.h#L188
C++