finagle-example: Expand finagle binary helper function in BUILD file
finagle-example: Expand finagle binary helper function in BUILD file

Problem

Bazel does not allow function definition in BUILD files.

Solution

One way is to move the `binary` function into a separate
pants-plugins function as well as into bazel translation, but
the usage is trivial enough that it's easier to expand them out.

Result

No functional change.

JIRA Issues: DPB-12589

Differential Revision: https://phabricator.twitter.biz/D513214

twitter/finagle,twitter/finagle,twitter/finagle,twitter/finagle,twitter/finagle