[SREP-1559] feat: check that when used, proxy url starts with http and do proxy hostname dns lookup to confirm connectivity

[T0MASD]

with this change testHTTPRequestToBackplaneAPI, checks that when used, proxy url starts with http and does proxy hostname dns lookup to confirm connectivity so user can clearly spot if there's an issue with config or connectivty

[openshift-ci]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (main@bbcffa9). Learn more about missing BASE report.
⚠️ Report is 98 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #756   +/-   ##
=======================================
  Coverage        ?   53.29%           
=======================================
  Files           ?       86           
  Lines           ?     7104           
  Branches        ?        0           
=======================================
  Hits            ?     3786           
  Misses          ?     2849           
  Partials        ?      469           

Files with missing lines	Coverage Δ
pkg/cli/config/config.go	86.94% <100.00%> (ø)

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[samanthajayasinghe]

Thanks for the PR @T0MASD ,
Please follow the PR guidelines next time as best practice.

[T0MASD]

/hold
while I update the commit message

[T0MASD]

/unhold

[T0MASD]

/hold while I fix race condition in a test

[samanthajayasinghe]

/test all

[samanthajayasinghe]

@T0MASD seems all tests are fine , do you need adjust more tests ?

[xiaoyu74]

/test all

[xiaoyu74]

/test images

[openshift-ci]

@T0MASD: all tests passed!

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