Investigate and identify ways to reduce .NET build drop size

The .NET build drops are huge and creeping upwards in size. We need to identify where the size is coming from and develop a plan to reduce that size, or we will start to see problems with downloading the drop and creating the layouts.

We should:
- Identify the total size of the download
- Identify the total size on disk, which may be different due to extra copies of files
- Identify artifacts that are duplicated on the whole in the download and on disk
- Identify artifacts that are duplicated within other containers (e.g. foo.dll in more than one package)
- Identify strategies to reduce the total size.

Not only is the large size a problem when attempting to complete the staging build due to disk space issues, but the download/artifact upload size has implicates for official and staging build performance.