Generate coverage report for new code and show all reports in GH step summary

[papa99do]

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
  Operational improvement

• What is the current behavior? (You can also link to an open issue here)

• we do not generate coverage report for new codes only
• we do not generate test report for largemodel unit test
• we do not display test and coverage summary in GH step summary

• What is the new behavior (if this is a feature change)?

• generate coverage report for new codes only ( we do not fail on the coverage threshold for now until we merge the coverage report of largemodel and unit tests)
• generate test report for largemodel unit test
• display test and coverage summary in GH step summary

• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)
  No

• Have unit tests been run against this PR? (Has there also been any additional testing?)
  No

• Related Python client changes (link commit/PR here)
  No

• Related documentation changes (link commit/PR here)
  No

• Other information:

• Please check if the PR fulfills these requirements

• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes/features)
• Docs have been added / updated (for bug fixes / features)

[adityabharadwaj198]

Majorly I have only 1 comment:
we should also fail the job / mark the PR as unable to merge if the test coverage percentage is below a certain threshold. Suggestions:

1. test coverage > 90%
2. New line coverage > 95%
3. New branch coverage > 95%

Further we could introduce some condition like "new test coverage of the codebase should improve by 0.1% from current test coverage".

[papa99do]

@adityabharadwaj198 , Thanks for the comments.
The fail-on-coverage change will come later. We need to combine coverage report for unit-test run and largemodel-unit-test run to make it work. Otherwise, any change that's only covered by one of the test run will fail the other one.