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[FelixS90]

Description

Use codecov to have fullstack code coverage support in PR, dashboard in one solution
No need for any other third party actions

Fixes #8

Note:
Status checks for branch policy need to be updated after merging this PR since job names have changed -> will take care about it.
Actions previously added to the allowed actions in the branch policy need to be removed again -> will take care about it.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

PR
https://app.codecov.io/gh/ZEISS/czicompress/tree/8-use-codecov-to-monitor-code-coverage
There is no component-based badge available yet, i.e. average coverage for czishrink and czicompress are displayed and badge. However, when clicking on badge, codecov dashboard shows everything.

Checklist:

• I followed the Contributing Guidelines.
• I did a self-review.
• I commented my code, particularly in hard-to-understand areas.
• I updated the documentation.
• I updated the version of czicompress following the README (Versioning) depending on the type of change
  • Bug fix -> PATCH
  • New feature -> MINOR
  • Breaking change -> MAJOR
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.

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