Use AppInstance type instead of App for get/list of Jobs

[tylerslaton]

In order to properly work with Manager, we should be using the AppInstance (internal) type for Apps. Since the Jobs is essentially a wrapper around the AppStatus.Jobs section of an App's status this is essential to properly work in Manager.

This also removes a section of code the client that is not needed and blocks the creation of the JobRestart sub resource in manager.

Checklist

• The title of this PR would make a good line in Acorn's Release Note's Changelog
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