Gather assembly references

Merged
TI
1y ago
+323-174

Fixes #1197
Fixes #2344
Fixes #2371
Also fixes legacy packages.config issues with CsProjClassicNetToolchain (no open issue, but was mentioned in https://github.com/dotnet/BenchmarkDotNet/issues/2405#issuecomment-1683212942).
And this is a pre-requisite to adding support for extern alias (#2289).