Guidance on aliases versus fully qualified names for using statements

[kendrahavens]

In reference to dotnet/roslyn#38539
A pattern in java development is using aliases to avoid type name conflicts rather than adding the fully qualified name. (This is for cases when pulling in the full namespace would cause many collisions.) We see alias usage rarely in C#, but it does occur. Instead of adding another style option to allow users to prefer one over the other, we’d like to know if C# should have opinionated guidance here.