Add support for consuming both docker-tools and arcade

[MichaelSimons]

Repo's currently cannot take a dependency on both docker-tools and arcade. There is value in "docker" repos using arcade as it provides common infra around acquiring .NET, bin placing artifacts in a common artifacts directory, common build script, etc. This is something I encountered with https://github.com/dotnet/dotnet-buildtools-prereqs-docker/pull/1359.

Currently if a repo tries to consume both, there is a conflict on the eng/common directory and both will stomp on each other's changes. There may be additional issue but this was the first I encountered which seems like it would be easy to address by a simple rename.