Allow changing parameter's display name at runtime

[murl-digital]

I'd like to be able to change the display name of a parameter after initialization, which would be, for example, automation slots for a complex plugin. It seems like this is possible with CLAP after a quick discussion in the rust audio discord (link), and it might be with VST3. I'd be happy to open a PR for this myself, but I'm starting with an issue for discussion and info gathering