Improve "spin prune" and optimize SSH experience

[jaydrogers]

What this PR does

This PR will address the following issues:

spin prune is not clearing registry or Ansible collections cache

We found that some cache files were being removed, but not everything. This PR ensures:

• Spin Cache
• Ansible Collections Cache
• Local Docker Registry cache

The local registry is no longer running as root

When users were running spin deploy, it was starting the registry as the default root user within the container. We've now added the --user flag to set the registry to to run as the current running user id and group id. This improves experiences for running everything as an unprivileged user.

Add support for SSH_AUTH_SOCK on Linux

We added the ability for the SSH Auth Socket to be set and work with Linux and WSL2 hosts.

Next steps

Before merging, I need to do the following:

• Run some final tests that WSL2 is deploying correctly
• Users should be able to run a spin prune and then a spin deploy multiple times without permission issues
• Test that SSH keys with passwords are working with WSL2 & macOS