Add unit tests for Formats tab

[alanb2718]

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[alanb2718]

Mostly completed via #1071. Unfortunately though it's difficult to test the Accordion part of the popup Format Form because onMount doesn't work correctly for components when doing unit tests. (These are places to enter the information for a translation.) I worked around this for the Account unit tests by factoring out a component that consisted of the accordion item, which could then be tested separately. This just tested the contents of the accordion item, which was all that was needed for the Account tab. For the Format Form, doing this would only test a small and not that interesting part of the functionality, since it would just test the initial contents of the translation, but wouldn't let you test editing and saving (as far as I can see). So the accordion part of the popup is currently not tested.

[alanb2718]

Now completed with #1152.