Microsoft.Data.SqlClient.SNI not deployed to _PublishedWebsites for an ASP.NET Web Application

### Background
For ASP.NET Web Applications it is common to build them providing `/p:OutDir=someDir` (or `/p:OutputPath=someDir`) parameter and then taking the `_PublishedWebsites\WebApp` contents and xcopy-ing them.

The custom SNI-deploying targets do support `OutDir` but not for a web app scenario - the SNI .dlls don't get copied to `_PublishedWebsites\WebApp\bin`.

### Steps to reproduce
A repo with a blank ASP.NET Web App and steps to reproduce: https://github.com/mbakalov/SqlClientSniRepro1

To reproduce, in VS command prompt do:
```bat
msbuild /t:Build /p:Configuration=Release /p:Platform="Any CPU" Example.sln /p:OutDir=C:\temp\output
```

The SNI .dlls get copied to `C:\temp\output`, but not to `C:\Temp\output\_PublishedWebsites\WebApp\bin`

### Expected behavior
Expected the SNI .dlls to be copied to the "bin" folder of the published website.

### Further technical details
Microsoft.Data.SqlClient version: 2.1.1
.NET target: net461

Related issue: https://github.com/dotnet/SqlClient/issues/441