Extract build from compile

Build becomes the new compile. It decides which project to compile and how. It checks for incremental preconditions
Compile's resonsibility is trimmed down to only knowing how to invoke the compiler on a project

src/Microsoft.DotNet.Tools.Pack/Program.cs

@@ -101,7 +101,7 @@ namespace Microsoft.DotNet.Tools.Compiler
 
                 argsBuilder.Append($" \"{path}\"");
 
-                var result = Command.Create("dotnet-compile", argsBuilder.ToString())
+                var result = Command.Create("dotnet-build", argsBuilder.ToString())
                        .ForwardStdOut()
                        .ForwardStdErr()
                        .Execute();