Add Task and Targets

[benvillalobos]

#21 and #18 rebased & combined

[benvillalobos]

Todo; add an end to end test for all the logic

[baronfel]

couple quick things as I was poking around :)

[baronfel]

nit: this should stay at 2.0.1

[baronfel]

it'll be important to document that the Entrypoint needs to be a fully-rooted path. I could see users doing something like

<ContainerEntrypoint>$(AppName)</ContainerEntrypoint>

and attempting to package up an executable at what is effectively /$(AppName), which won't exist.

Maybe there's some validation we can do here to save them: either checking that a fully-rooted path was provided, or attempting to 'root' a relative or un-rooted path against the ContainerWorkingDirectory.

[benvillalobos]

Cloud-based note to self:

mkdir "C:\temp\dir\newproject"

dotnet new console
dotnet new nugetconfig
dotnet nuget add source "C:\temp\dir\PackageUploads" -n local-folder
dotnet build "System.Containers.Tasks"
dotnet nuget push "C:\Path\To\Nupkg" --source local-folder
dotnet add package System.Containers.Tasks
dotnet publish --publishprofile=defaultcontainer