Add packit job copr and tests

[inknos]

Requires rpm-software-management/ci-dnf-stack#1405
Tests will fail. Once merged test with /packit test before merging.

Requirements to onboard:

• wrap our ci so that we don't have to reinvent the wheel
  • use the latest upstream ci-dnf-stack and the same scripts provided by us
  • respect the requirements of running destructive tests in separate containers
• provide copr builds for inspections

Key advantages:

• build rpms for all fedoras using copr
• run tests for all fedoras
• reproduce the tests locally (provided by tmt)
• possibility to run tests directly from ci-dnf-stack via /packit test rpm-software-management/dnf5#973 (provided that the pr has a packit build) Test tmt/packit integration ci-dnf-stack#1398

Future possible improvements:

• possibility to rerun part of the tests in the future via /packit test <sometest>
• possibility to split the test ci and run separate tiers for different systems

Once this PR gets merged and works, the old actions can be removed: #1008

[m-blaha]

/packit tests

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/packit test

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Thanks!