[OtelZap] Keep support for explicit Log Attributes

[pragmaticivan]

Howdy! Thanks for this great lib!

It used to support explicit log attributes which are widely used by many platforms where Log ingestion is done from the cluster, instead of the application via fluentbit. Having a way to add these attributes improves logging pipelines, where the cluster might add extra context to the log before it's sent to a provider.

The latest version seems to have removed that feature and assumes that apps are always responsible to send logs to a provider.

Thoughts?