I was looking for this exact feature for as long as there were containers in Firefox. Honestly, this should've been the default behavior.

The switch back to the default container is a bit jerky (it rapidly opens the tab in a current container, closes it, and opens again in the default one) and if you're opening a link in the same tab it won't work, it only works for new tabs, but that's good enough for me. Now I'll finally start to actually use containers.