[DOP-23126] added basic pytest-coverage-comment

[marashka]

Change Summary

Related issue number

Checklist

• Commit message and PR title is comprehensive
• Keep the change as small as possible
• Unit and integration tests for the changes exist
• Tests pass on CI and coverage does not decrease
• Documentation reflects the changes where applicable
• docs/changelog/next_release/<pull request or issue id>.<change type>.rst file added describing change
  (see CONTRIBUTING.rst for details.)
• My PR is ready to review.

[dolfinus]

Github Action cannot create comment in PR, probably because default token permissions are restricted to read-only:

syncmaster/.github/workflows/tests.yml

Lines 18 to 19 in 31baf09

	permissions:
	contents: read

We should add additional permissions to Tests done job:
https://docs.github.com/ru/actions/reference/workflows-and-actions/workflow-syntax#permissions
https://github.com/MishaKav/pytest-coverage-comment?tab=readme-ov-file#-troubleshooting

permissions:
  contents: write
  checks: write
  pull-requests: write

Also, we should pass following options to action to properly report coverage change:

with:
  default-branch: develop
  xml-skip-covered: true

And it would be nice to have a README badge showing develop branch coverage:
https://github.com/MishaKav/pytest-coverage-comment?tab=readme-ov-file#-advanced-features
Gist can be created within the organization, for token you can use ${{ secrets.AUTOMERGE_TOKEN }}.
Old Codecov badge can be removed.

[github-actions]

Coverage Report •

File	Stmts	Miss	Cover	Missing
TOTAL	4761	274	94%

report-only-changed-files is enabled. No files were changed during this commit :)

[dolfinus]

Let's address the badge comment above, and remove all Codecov-related files from repo

[dolfinus]

There is also a https://github.com/MobileTeleSystems/syncmaster/blob/develop/codecov.yml left, let's remove it, and implement coverage percent check as CI job step.