podman: Get the gateway by inspecting container network

[afbjorklund]

Closes #7951

[k8s-ci-robot]

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[medyagh]

looks good just needs the comment to be deleted

[codecov-io]

Codecov Report

Merging #7962 into master will increase coverage by 0.33%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #7962      +/-   ##
==========================================
+ Coverage   35.71%   36.04%   +0.33%     
==========================================
  Files         149      144       -5     
  Lines        9408     9196     -212     
==========================================
- Hits         3360     3315      -45     
+ Misses       5644     5480     -164     
+ Partials      404      401       -3     

Impacted Files	Coverage Δ
cmd/minikube/cmd/tunnel.go	5.26% <100.00%> (+0.13%)	⬆️
cmd/minikube/cmd/node_add.go	17.85% <0.00%> (-1.38%)	⬇️
cmd/minikube/cmd/start.go	15.61% <0.00%> (-0.12%)	⬇️
pkg/minikube/download/progressbar.go