fix: add egg info post install command for egg info setup mode

[alaeddine-13]

Egg info setup mode does not have a post install command associated with it in setup.py (unlike install and develop).
This means, jina post install commands will not be executed in some cases (includes autocompletes, setting needed environment variables,...).
This PR adds an egg info post install command to handle this case.

[codecov]

Codecov Report

Merging #5491 (14f763e) into master (6a6fafc) will decrease coverage by 1.12%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #5491      +/-   ##
==========================================
- Coverage   85.72%   84.60%   -1.13%     
==========================================
  Files         101       99       -2     
  Lines        6689     6643      -46     
==========================================
- Hits         5734     5620     -114     
- Misses        955     1023      +68     

Flag	Coverage Δ
jina	84.60% <100.00%> (-1.13%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...deployments/config/k8slib/kubernetes_deployment.py	64.70% <100.00%> (ø)
jina/clients/mixin.py	65.51% <0.00%> (-31.90%)	⬇️
jina/serve/runtimes/worker/request_handling.py	76.04% <0.00%> (-15.11%)	⬇️
jina/serve/runtimes/gateway/request_handling.py	85.04% <0.00%> (-10.29%)	⬇️
jina/jaml/parsers/executor/legacy.py	82.00% <0.00%> (-8.00%)	⬇️
jina/orchestrate/pods/helper.py	82.69% <0.00%> (-7.70%)	⬇️
jina/clients/base/grpc.py	84.00% <0.00%> (-6.67%)	⬇️
jina/serve/runtimes/gateway/websocket/app.py	73.02% <0.00%> (-5.93%)	⬇️
jina/serve/streamer.py	92.85% <0.00%> (-3.58%)	⬇️
jina/clients/base/http.py	93.05% <0.00%> (-2.78%)	⬇️
... and 11 more

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.