Fix plugin templates (#6557)

We are using `pkgname` everywhere as target names and also as dependency references, but plugin targets were using `typeName` which leads to newly created plugin packages being broken if the difference was meaningful (e.g. if the name includes dashes).

(cherry picked from commit 78cceb7)

Author: neonichu

Sources/Workspace/InitPackage.swift

@@ -287,15 +287,15 @@ public final class InitPackage {
                 } else if packageType == .buildToolPlugin {
                     param += """
                             .plugin(
-                                name: "\(typeName)",
+                                name: "\(pkgname)",
                                 capability: .buildTool()
                             ),
                         ]
                     """
                 } else if packageType == .commandPlugin {
                     param += """
                             .plugin(
-                                name: "\(typeName)",
+                                name: "\(pkgname)",
                                 capability: .command(intent: .custom(
                                     verb: "\(typeName)",
                                     description: "prints hello world"