Add unit tests for filename input handling across all workflow framew… #447

Job	Run time
black	12s
quantumespresso	33m 19s
arithmetic	2m 40s
coverage	1m 25s
unittest_matrix (ubuntu-latest, 3.12)	1m 14s
unittest_matrix (macos-latest, 3.12)	2m 18s
documentation	36s
unittest_matrix (ubuntu-latest, 3.11)	1m 11s
pip_check	1m 2s
nfdi4ing	6m 52s
	50m 49s

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