Tab Label Improvements

[sosiology]

Arrow Missing on Left Hand Side

1. In published mode, the left arrow seems to be missing, and the tab is not aligned with the rest of the frame. I assume that the arrow should only appear once the user scrolls, but the indent before the first tab looks a bit strange to me. see: https://test.visualize.admin.ch/en/v/tFKBIr7nwSRG?dataSource=Prod and screen shot below

2. Add Character Limit to Tabs to avoid really long labels. I noticed there is no character limit on the tab label...should we consider introducing a character limit for the tab labels to avoid extremely long labels as can be seen here: https://test.visualize.admin.ch/en/v/tFKBIr7nwSRG?dataSource=Prod. If the label is very long, it may be hard for the user to discover additional charts in a chart published in tab layout. This would be a new issue 💡

Originally posted by @sosiology in https://github.com/visualize-admin/visualization-tool/issues/1714#issuecomment-2379587575