Refactor the build scripts

- Bifurcate Package and Publish targets to enable signing.
- Move publish from bash/ps into c#.
- Create multiple targets to create MSIs and Bundles.

scripts/dotnet-cli-build/InstallerTargets.cs

@@ -0,0 +1,51 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.IO.Compression;
+using System.Runtime.InteropServices;
+using Microsoft.DotNet.Cli.Build.Framework;
+using Microsoft.Extensions.PlatformAbstractions;
+
+using static Microsoft.DotNet.Cli.Build.Framework.BuildHelpers;
+
+namespace Microsoft.DotNet.Cli.Build
+{
+    public class InstallerTargets
+    {
+        [Target(nameof(MsiTargets.GenerateMsis),
+        nameof(MsiTargets.GenerateBundle),
+        nameof(InstallerTargets.GeneratePkg),
+        nameof(InstallerTargets.GenerateDeb))]
+        public static BuildTargetResult GenerateInstaller(BuildTargetContext c)
+        {
+            return c.Success();
+        }
+
+
+
+        [Target]
+        [BuildPlatforms(BuildPlatform.OSX)]
+        public static BuildTargetResult GeneratePkg(BuildTargetContext c)
+        {
+            var version = c.BuildContext.Get<BuildVersion>("BuildVersion").SimpleVersion;
+            var pkg = c.BuildContext.Get<string>("InstallerFile");
+            Cmd(Path.Combine(Dirs.RepoRoot, "packaging", "osx", "package-osx.sh"),
+                    "-v", version, "-i", Dirs.Stage2, "-o", pkg)
+                    .Execute()
+                    .EnsureSuccessful();
+            return c.Success();
+        }
+
+        [Target]
+        [BuildPlatforms(BuildPlatform.Ubuntu)]
+        public static BuildTargetResult GenerateDeb(BuildTargetContext c)
+        {
+            var env = PackageTargets.GetCommonEnvVars(c);
+            Cmd(Path.Combine(Dirs.RepoRoot, "scripts", "package", "package-debian.sh"))
+                    .Environment(env)
+                    .Execute()
+                    .EnsureSuccessful();
+            return c.Success();
+        }
+    }
+}