[display] rename support

I was playing with supporting rename in vshaxe using `@usage` display mode and stumbled upon a couple issues for which I think we may want a separate display mode similar to `@usage`, but more precise about what _name_ is.

For example, when doing a type rename, we want to report positions of actual name to be changed, not the whole expression which might be a fully-qualified path:
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Another useful addition (as seen in the gif above) would be to report the name of the actual renamed symbol, because calculating it in the IDE doesn't seem right as well.