Name package-level code for its feature

Name package-level code for its feature

The go-code skill now asks for a feature prefix on each package-level
name that belongs to one feature or integration, and on the names of its
files. A name stays generic only when more than one feature uses it. All
the code is in one main package, so every name is visible in every file,
and generic names such as a client, a request, or a poll interval of one
service read as if they belong to all of them.

The skill also asks for unexported names, because an exported name has
no effect in a main package, and for initialisms in one case.