Add support for Stringers field type

[JeanMertz]

Zap has support for Stringer, which indeed makes the log entries a bit more simple to construct. However, the real power to me would be if it also had a Stringers (plural) function.

Right now, if you have an array of objects that implement fmt.Stringer, you have to manually loop them, extract the strings, and then call zap.Strings. It would be a lot cleaner if we could simply pass them as-is to Stringers and let Zap handle the rest.

[akshayjshah]

What would the signature of zap.Stringers be? If I have a type *Foo that implements io.Stringer, you can't pass []*Foo as []io.Stringer - you have to allocate a new slice and copy over each element.

[saurabh95]

With generics, this is possible to implement now.
The PR to add this functionality is already merged and released in the latest version: #1155

[abhinav]

Yep! Done with #1155. Thanks, @saurabh95.