* Add x-pack plugin for new platform server licensing information
* Update x-pack translations
* Implement core plugin interface for licensing plugin:
* Rename references to service to plugin
* Use CoreStart in licensing start method
* Fix outstanding reference error
* Fix type check errors
* Address outstanding review comments
* Fix type error in tests
* Address review comments, move polling logic to standalone
* Split up test files
* Fix bad reference in test
* Use relative reference to poller util
* Add more plugin tests to address review comments
* Fix different manners of config generation in licensing plugin
* Update test fixtures
* Fix path to test fixtures