* Remove unnecessary \ incorrect package references
* Remove extraneous build outputs in the tasks project that weren't present when the tasks were in Razor.Design
Loading multiple versions of a task assembly result results in MSBuild on .NET Core to fail.
Addressing this by moving the tasks in to the Sdk and renaming it. This should avoid
immediate issues for a 2.1 and 2.2 project co-existing and future proofs 2.2 and later.
Fixes https://github.com/aspnet/Razor/issues/2553
Ryan Nowak
Pranav K