Feature request: Make service network alias support templating.

#24973 tries to do something similar automatically but is blocked on moby/swarmkit#1242... One workaround idea that has received several 👍 from other community members is to make network aliases support templating (e.g.: #24787 (comment), #24787 (comment), #24787 (comment)). I couldn't find an issue devoted to that specific request so I figured I'd file this one.