To further align with the API, we return custom JSON in order to display a
`visible` field rather than `hidden` -- a `PUT` request expects `visible`, while
a `GET` request returns `hidden`.
This also allows us to rename the `jobsetinputs` field to `inputs` for the same
reason: `PUT` expects `inputs`, while `GET` returns `jobsetinputs`.
1. Configure the in-memory Hydra instance with a null path input cache
time to avoid caching slowing the test down.
2. Use the Catalyst::Test helpers so we talk to the application and skip
needing to actually run a webserver.
3. Change path references to use a tempdir, since this is running while
other tests are also running.
4. Change the login flow to save a cookie and pass it manually. A bit
weird, but it avoids a dependency on heavier browser-mimicking
libraries.
