Allow parsing of negative DateTime64 and DateTime with fractional part from short strings

Why it matters

Previously, DateTime64 and DateTime types with fractional parts could not be correctly parsed when the string representation was short and included negative values. This feature enables correct interpretation of such values, enhancing input flexibility and data accuracy for users working with timestamps that can be negative or include fractional seconds.

How to use it

Users can now input negative DateTime64 and DateTime values with fractional parts directly as short strings without additional formatting or casting. The parsing behavior is automatically supported in queries and data ingestion where these types are used.