Implement retry functionality for the podman plugin

[psss]

The podman pull command sometimes fails to fetch the desired images because of (what seems to be) temporary network errors, see #2063 for some details and examples. There is a limited retry feature included in podman itself, but currently it's not configurable:

• Way to specify number of image pull attempts and the pause between attempts containers/podman#19770

Let's implement a simple retry functionality to prevent random failures until the above-mentioned feature is available directly in podman.