feat: allow explicitly specifying provider type

[austince]

What does this PR do?

Allows explicitly setting the provider type via an environment variable or the properties file in addition to the autodetection introduced in #982

Why is it important?

Autodetection does not work in all scenarios, like when using the Podman Desktop compatibility mode since the docker host still points to the docker unix socket (which has been soft linked).

Related issues

Mentioned in #604 (comment)

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[mdelapenya]

Hey @austince, as I commented in #1991 (reply in thread), I think we should disregard the manual configuration of the provider but instead make the existing auto-discovery mechanism to detect the provider in a more robust manner.

If you agree, I'd close this PR in favour of another one that makes the mechanism more robust, deprecating the existing non-default providers. Wdyt?

[austince]

If you agree, I'd close this PR in favour of another one that makes the mechanism more robust, deprecating the existing non-default providers. Wdyt?

Would seem to make sense, though a proposal of how to do so would be good to understand what it would take\ -- what are you thinking for this one?

[godart]

As mentiones in #2264: Maybe using '/info/' '/version' requests to determine if Podman is used.

~> curl  --unix-socket /var/run/docker.sock "http://v1.41/version"  -s | jq '.Components'
[
  {
    "Name": "Podman Engine",
    "Version": "5.0.1",
    "Details": {
         <... snip />
    }
  },
  {
    "Name": "Conmon",
     <... snip />
  },
  {
    "Name": "OCI Runtime (crun)",
     <... snip />
  }
]