Replace temporal _generic kernels with dyn

[tustvold]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

The temporal _generic methods exist to handle dictionaries, but do so in a way inconsistent with the other kernels such as arithmetic:

• Don't return a dictionary array
• Require explicitly downcasting the dictionary

Describe the solution you'd like

Instead of _generic kernels I would like an _dyn kernel that takes an &dyn Array.

In the case of a dictionary, this will recurse calling itself on the dictionary values, and then use
https://docs.rs/arrow-array/latest/arrow_array/array/struct.DictionaryArray.html#method.with_values to replace the values with the newly computed

Describe alternatives you've considered

We could not do this

Additional context

FYI @viirya

[viirya]

Don't return a dictionary array
Require explicitly downcasting the dictionary

I think that arithmetic kernels don't return a dictionary array for input dictionaries?
But for temporal kernels, it sounds reasonable to do as the keys should be the same.

[alamb]

label_issue.py automatically added labels {'arrow'} from #3041