Add spacing between contributor chips on dandiset pages.

As shown in the attached screenshot, chips doesnt have spacing and therefore look jumbled:
<img width="1527" height="148" alt="Image" src="https://github.com/user-attachments/assets/54e20499-9e81-4c5a-a7f3-b8d61103e463" />

Add 12px - 16px spacing between chips (horizontal and vertical).