Require at least 1 child in JSX components

[Mrtenz]

This changes the types and validation for JSX components to require at least one child. Previously it was possible to do something like <Box children={[]} />, but this will now result in an error.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 94.33%. Comparing base (491f8fb) to head (51a51ff).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #2466 +/- ## ======================================= Coverage 94.33% 94.33% ======================================= Files 438 438 Lines 9037 9039 +2 Branches 1384 1384 ======================================= + Hits 8525 8527 +2 Misses 512 512 ```

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