ui-finc-select: adapt index.test.js and add route tests

See

In test suite src/index.test.js is randomly failing these two tests:
should render SourceViewRoute and should render CollectionViewRoute with this error:

I suggest it is, because the view-component is called with required data for the <List>-component, but in the test the data is empty.

The mentioned test should not test the rendering of individual <...Route> components, but the rendering of the <FincConfig> component.
This would include the following tests:

• <Settings> should be rendered depending on showSettings

• <...Route> components should be rendered depending on path

• All components should be mocked

Tests for individual <...Route> components should go into their corresponding files (e.g. SourceCreateRoute.test.js).