File Nesting: Warnings from File Nesting are returning the wrong data for Error List properties

The file nesting feature is populating the error list but has two problems with the data its returning:


1) ~It's always returning a value for `StandardTableKeyNames.FullText`, confusing the Error List into thinking that it has expandable "Description", when it's just repeating the contents of the text. You can see in contrast to the Compiler error which does the right thing. See src\Microsoft.VisualStudio.ProjectSystem.VS.Implementation\Build\BuildErrorsTableDataSource.cs for the correct way to handle this. It should only return FullText for errors that span multiple lines.~ PR: [278832](https://devdiv.visualstudio.com/DevDiv/_git/CPS/pullrequest/278832)

2) It isn't correctly returning a value for `StandardTableKeyNames.ProjectGuid` so "Project Rank" isn't being set.

3) It isn't returning a value for `StandardTableKeyNames.ProjectName`, so "Project" column isn't being set