Can the analysis server report in an IDE that multiple instances or versions of any pub package are in play

[srawlins]

See #48925 for the motivation.

There are several ways the analysis server can read from multiple package config files (mono repos, overly broad analysis root, pub packages with nested example packages or testing packages (e.g. the camera plugin living in the plugins monorepo).

Different version solves means that package:path 1.0.0 is fetched for one package, but package:path 1.0.1 is fetched for another. This means that there can be multiple copies of various elements in analyzer's memory, which will duplicate elements in Search, etc. In #48925, this results in multiple instances of plugin code running in multiple isolates.

What to do? Should analysis server alert the user in some way?