Support for type coercion for a (Timestamp, Utf8) pair

[andre-cc-natzka]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
At the moment DataFusion supports type coercion for (DataType::Time, DataType::Utf8) and (DataType::Date, DataType::Utf8) pairs, but does not account for type coercion for (DataType::Timestamp, DataType::Utf8).

Describe the solution you'd like
We need to add support for type coercion for a (DataType::Timestamp(_, _), DataType::Utf8) pair (all time units considered) into a DataType::Timestamp(TimeUnit::Nanosecond, _). The reason why the output type has to consider nanosecond accuracy is the fact that this is the only time unit supported by Arrow.

Describe alternatives you've considered

Additional context