Improve files helper specs
Improve files helper specs

Test whether custom partials are really used. Reduce volume of tests for
specific fields on file types and nested file types.

tilsammans/pageflow,Modularfield/pageflow,Modularfield/pageflow,codevise/pageflow,tf/pageflow-dependabot-test,tf/pageflow,tf/pageflow,codevise/pageflow,codevise/pageflow,tf/pageflow,codevise/pageflow,tilsammans/pageflow,Modularfield/pageflow,tilsammans/pageflow,tf/pageflow-dependabot-test,tf/pageflow,Modularfield/pageflow,tilsammans/pageflow,tf/pageflow-dependabot-test,tf/pageflow-dependabot-test