[Ruby] Add Google::Protobuf::Timestamp.from_time

[DerekStride]

Previously, you would have to instantiate a timestamp class then call #from_time on that object to mutate its state. Instead provides a mechanism to instantiate the object with the correct state.

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[jufemaiz]

I can only assume that this was abandoned @DerekStride ?

[DerekStride]

I closed it because of a lack of involvement from the maintainers but I still think this is a valuable change

[jufemaiz]

Ok sweet. See #8254 (also expands to resolve similar issue with other well known types)