Fix UUList data typing

[This commit](https://github.com/CentreForDigitalHumanities/Vue-lib/pull/10/commits/cc9d2416966726238c051876f239c8385e699ae1) removed `outFile` (which is deprecated), so types are now dispersed in various individual type files. From what I could read online, this seems to be the preferred approach. However, this also breaks the typing of the `data` prop for the slots of UUList.

You can check this out for yourself in `uu-list.vue`. The data prop used to be properly typed, but now it's just `any[] | undefined`.

Using `defineSlots()` is of no avail. The only solution I have found to 'work' is to type assertions in the consuming component, e.g. in DIAPP's GraphQLList:

Needless to say that this should not be necessary, and the output of UUList should be properly typed again.

Start in uu-list.vue and compare its current slot data typing with the earlier version referenced by the linked commit. Read the dispersed individual type files and inspect the consuming DIAPP GraphQLList example to understand the expected inferred type. Done means UUList slot data is properly typed again without type assertions in consuming components.

Written by the indexing model from the issue text.