[fix] Added support for cmd-like auth

[rennokki]

Some clusters like GKE authenticates users by renewing a token at specific intervals. For example, in the following kubeconfig file, the user token in kubectl is taken from a CLI response:

users:
- name: gke_cluster
    user:
        auth-provider:
            config:
                cmd-args: config config-helper --format=json
                cmd-path: S:\GCSDK\google-cloud-sdk\bin\gcloud.cmd
                expiry-key: '{.credential.token_expiry}'
                token-key: '{.credential.access_token}'
            name: gcp

With this PR, the package will run the cmd-path and cmd-args with Symfony Process to retrieve the token and authenticate the requests.

[codecov]

Codecov Report

Merging #205 (52f1769) into master (8b21b67) will decrease coverage by 0.00%.
The diff coverage is 94.11%.

@@             Coverage Diff              @@
##             master     #205      +/-   ##
============================================
- Coverage     94.99%   94.98%   -0.01%     
- Complexity      696      700       +4     
============================================
  Files            70       70              
  Lines          1697     1714      +17     
============================================
+ Hits           1612     1628      +16     
- Misses           85       86       +1     

Impacted Files	Coverage Δ
src/Kinds/K8sPod.php	94.30% <ø> (ø)
src/Traits/Cluster/MakesHttpCalls.php	100.00% <ø> (ø)
src/Traits/Cluster/AuthenticatesCluster.php	97.77% <90.90%> (-2.23%)	⬇️
src/Traits/Cluster/LoadsFromKubeConfig.php	93.75% <100.00%> (+0.41%)	⬆️

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