Automate opening external links in a new tab?

Not sure whether this is possible to automate, or even if it's generally desirable (it's certainly my preference, and a convention that we have followed in earlier releases, but that doesn't mean it has to be there). An indication of how much effort this would be would help to determine whether this should be implemented!

The issue names no files, tests, or entry points. First inspect how external links are rendered across the documentation assets and determine which layer controls link behavior; done means confirming whether automatic new-tab opening is desirable and defining the implementation scope.

Written by the indexing model from the issue text.