This is not necessarily Ignition-specific but I know there are many of us that use Allen Bradley and other modern PLCs for our projects.
As of late I've felt that exporting AOIs and rungs/routines to a file location as a "library" has been a bit lacking when it comes to the dev experience.
Does anybody know of plugin tools or 3rd party programs that help maintain/use a library like this?
Rockwell has the Application Code Manager tool.
I've not used it personally... we looked into it and found that our Toolkit didn't have a license for it so we didn't move forward.
I've not bugged our rep to see if he can swing us a license yet.
Hesitant to get into yet another AB software product 
Copia looks very nice.
Anybody have experience with that?
Found this discussion from 2022
I've heard good things about it but never used it. Also heard that it's expensive.
Beckhoff TwinCAT 3.1 with Git integration using Microsoft Azure free as the remote repo and then making standard code library project(s) referenced in production projects is a thing of beauty that made it possible to add additional programmers to a larger project on a short timeline. I don't know how we could have done it with Allen-Bradley. And in most cases you can update a running PLC project to an updated version of your standard code library online (without stopping the plant). It hurts when I have to go back to Allen-Bradley for something!