Ability to run portal-hive tests directly against local binary of the client

[kdeme]

When working on portal-hive failures that are related to a client, currently we need to rebuild the client its docker image.
How long this takes, does depend on the implementation of the Dockerfile for the client, but will always take more than then just building it locally, which you usually would do anyhow when testing.

It would be nice if we had some special debugging runner that could run the tests from a provided local binary.

This is not a crucial nor urgent feature, but it does seem there is some interest for this at least.

[fjl]

We have solved this problem in upstream hive by providing a Dockerfile.local for some clients. Hive can be made to use this file by way of the --client-file option. Since the portal simulators have already been moved to upstream hive, you can use this now if you send a PR with a working Dockerfile.local.