feat: support importing internal ALBs for backend services

[huanjani]

Related: #5438. Integ test changes in #5483.

#5483 adds the Load Balancer DNS name to the service as an env var (and therefore appears in svc show output. However, it is not (yet) included in URI output as a recommended action in svc deploy output.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the Apache 2.0 License.

[github-actions[bot]]

🍕 Here are the new binary sizes!

Name	New size (kiB)	size (kiB)	Delta (%)
macOS (amd)	58084	58072	+0.02
macOS (arm)	59152	59136	+0.03
linux (amd)	50936	50924	+0.02
linux (arm)	50176	50180	❤️ -0.01
windows (amd)	47976	47964	+0.03

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 46.98795% with 44 lines in your changes are missing coverage. Please review.

Project coverage is 69.99%. Comparing base (48f092a) to head (f505a34). Report is 4 commits behind head on mainline.

Files	Patch %	Lines
...al/pkg/deploy/cloudformation/stack/transformers.go	15.38%	22 Missing :warning:
internal/pkg/cli/deploy/backend.go	72.50%	8 Missing and 3 partials :warning:
...nal/pkg/deploy/cloudformation/stack/backend_svc.go	23.07%	8 Missing and 2 partials :warning:
internal/pkg/cli/svc_deploy.go	0.00%	1 Missing :warning:

Additional details and impacted files

@@             Coverage Diff              @@
##           mainline    #5490      +/-   ##
============================================
- Coverage     70.01%   69.99%   -0.02%     
============================================
  Files           303      303              
  Lines         46638    46714      +76     
  Branches        299      299              
============================================
+ Hits          32655    32699      +44     
- Misses        12396    12424      +28     
- Partials       1587     1591       +4     

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.