Qmctl tests

[ArtiomDivak]

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Closes: https://issues.redhat.com/browse/VROOM-28614

Summary by Sourcery

Add a comprehensive bash-based functional test suite for the qmctl CLI, integrating FMF metadata and fixtures to validate show, exec, execin, and cp subcommands.

Tests:

• Introduce a new tests/qmctl-test directory with orchestration script to install dependencies and run individual command tests.
• Add bash scripts to test qmctl show, exec, execin, and cp subcommands with exit-code checks.
• Include fixture files and a check_output.sh helper script for output verification.
• Add main.fmf metadata to register the new tests with the FMF framework.