**What this PR does / why we need it**:
The --pod-infra-container-image parameter allows the user to specify
an arbitrary image to be used as the pod infra container (AKA
sandbox), an internal piece of the dockershim implementation of the
Container Runtime Interface.
The dockershim does not have access to any of the pod-level image pull
credentials configuration, so if the user specifies an image from a
private registry, the image pull will fail.
This change allows the dockershim to read local docker configuration
(e.g. /root/.docker/config.json) and use it when pulling the pod infra
container image.
**Which issue this PR fixes**: fixes#45738
**Special notes for your reviewer**:
The changes to fake_client for writing local config files deserve some
attention.
**Release note**:
```release-note
NONE
```
The test was originally in docker_manager_test.go (now removed). I
copied and adapated the logic for the new test.
Also move the original test fixtures needed for the test.
* Properly return ImageNotFoundError
* Support inject "Images" or "ImageInspects" and keep both in sync.
* Remove the FakeDockerPuller and let FakeDockerClient subsumes its
functinality. This reduces the overhead to maintain both objects.
* Various small fixes and refactoring of the testing utils.
We have observed that, after failing to create a container due to "device or
resource busy", docker may end up having inconsistent internal state. One
symptom is that docker will not report the existence of the "failed to create"
container, but if kubelet tries to create a new container with the same name,
docker will error out with a naming conflict message.
To work around this, this commit parses the creation error message and if there
is a naming conflict, it would attempt to remove the existing container.
