Update lightning serve CLI

[aniketmaurya]

What does this PR do?

Update the Lightning serve command for deployment.

lightning serve server.py -> Deploy on cloud

lightning serve server.py -> Deploy locally

Before submitting

• Was this discussed/agreed via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure to update the docs?
• Did you write any new necessary tests?

PR review

Anyone in the community is free to review the PR once the tests have passed.
If we didn't discuss your PR in GitHub issues there's a high chance it will not be merged.

Did you have fun?

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89%. Comparing base (f30b7bb) to head (6a29541).
Report is 1 commits behind head on main.

Additional details and impacted files

@@         Coverage Diff         @@
##           main   #460   +/-   ##
===================================
  Coverage    89%    89%           
===================================
  Files        37     37           
  Lines      2155   2155           
===================================
  Hits       1911   1911           
  Misses      244    244           

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