Add application resource

[jtcarnes]

AWX allows an API for creating Authentication applications (found here).

Currently, there is no resource for creating those applications. These would be helpful for users who want to declaratively manage their authentication configuration.

This would require one resource (applications) and one data source.

If its something of interest, I'm happy to work on this.

[denouche]

Hello @jtcarnes , we updated the goawx client in #14 to add the Application client.

If you need the Application resource and datasource feel free to submit a PR here!

Thank you!