Don't convert built-in (reserved) pytest markers to allure tags (fix #817)

[sharovd]

Context

• Fix the issue to prevent saving marks with parameters as labels → tag #817

• Code changes:

  • The pytest_markers(item) method in utils.py has been simplified - now only "simple" user-defined pytest markers are converted to allure tags. Built-in (reserved) markers (e.g. skip, xfail, etc.) are now ignored. The approach was taken from allure-pytest-bdd implementation

• Unit tests changes:

  • Existing tests in tag_test.py have been updated, new tests have been added for each built-in (reserved) marker to verify they are ignored
  • Renamed both the update and the new tests to make their purpose clearer
  • Removed test_pytest_marker_with_kwargs_native_encoding as a duplicate of test_pytest_marker_with_kwargs_utf_encoding - they looked identical
  • Updated the affected test in pytest_rerunfailures_test.py accordingly

Checklist

• Sign Allure CLA
• Provide unit tests