* refactor(Plugins/Admin): add a type for version coming back from the API
* refactor(Plugins/Admin): only add necessary version information to the state
* test(Plugins/Admin): add a mock for a CatalogPlugin
* test(Plugins/ADmin): add a mock for a LocalPlugin
* test(Plugins/Admin): add a test for a RemotePlugin
* test(Plugins/Admin): add helpers for mocking plugin states
* refactor(Plugins/Admin): mock the Redux state instead of the API responses
This makes it simpler to add new test cases and also makes
the tests easier to reason about.
* refactor(Plugins/Admin): mock the Redux state instead of the API responses
