2249: Cleanup hover r=matklad a=kjeremy
Take advantage of classify_name to consolidate multiple hover paths. This isn't quite as clean as I want it to be (`no_fallback` bool is wonky). There's a relationship between `HoverResult` being empty and the range that is a little warty.
Also I noticed that HoverResults are always marked as exact and have been for quite a while... maybe that should be removed in another PR.
Co-authored-by: Jeremy Kolb <kjeremy@gmail.com>
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