Make table sorting options more obvious

Summary

Following on from discussion in gitlab#301082 (comment 570459360), are there options we can explore to make the table sorting more obvious to users?

Ahh, I have to click on the Time column for the arrow to display. It wasn't obvious to me that sorting by the Time column was even an option because I didn't see the arrow.

I wonder if there is some way to make this more obvious @ekigbo ?

This feels familiar like it tripped me up once before in the UI. Ah yes, in the DevOps Adoption table.

@npost Do we have any other design options for sorting?

Proposal

Add blue hover highlighting as described in @ameliabauerly's comment