Update to i18n 0.5.1 and add i18n-clj job to CI pipeline

The various Trapperkeeper (and related Clojure library) projects which use i18n should be updated to the latest clj-i18n version, 0.5.1 and have their CI pipelines updated to include the i18n-clj template. This will allow the locale POT files to be updated automatically by CI whenever any externalized strings need to be changed based on the latest Clojure code in the projects. This avoids the need to update the files at compile time and include those changes on a per-PR basis.

Repos to update include:

• trapperkeeper
• tk-webserver-jetty9
• tk-metrics
• tk-auth
• tk-filesystem-watcher
• jvm-ssl-utils
• http-client
• tk-status
• ring-middleware