Use the flat package structure (no separate module directory) for the plugin code

Author: abertelrud

Sources/Workspace/InitPackage.swift

@@ -388,10 +388,10 @@ public final class InitPackage {
             progressReporter?("Creating \(plugins.relative(to: destinationPath))/")
             try makeDirectories(plugins)
 
-            let moduleDir = plugins.appending(component: "\(pkgname)")
+            let moduleDir = plugins
             try makeDirectories(moduleDir)
 
-            let sourceFileName = "plugin.swift"
+            let sourceFileName = "\(pkgname).swift"
             let sourceFile = try AbsolutePath(validating: sourceFileName, relativeTo: moduleDir)
 
             var content = """

Tests/WorkspaceTests/InitTests.swift

@@ -171,7 +171,7 @@ class InitTests: XCTestCase {
             XCTAssertMatch(manifestContents, .and(.contains(".plugin("), .contains("targets: [\"MyCommandPlugin\"]")))
             XCTAssertMatch(manifestContents, .and(.contains(".plugin("), .contains("capability: .command(intent: .custom(verb")))
 
-            let source = path.appending("Plugins", "MyCommandPlugin", "plugin.swift")
+            let source = path.appending("Plugins", "MyCommandPlugin.swift")
             XCTAssertFileExists(source)
             let sourceContents: String = try localFileSystem.readFileContents(source)
             XCTAssertMatch(sourceContents, .contains("struct MyCommandPlugin: CommandPlugin"))
@@ -200,7 +200,7 @@ class InitTests: XCTestCase {
             XCTAssertMatch(manifestContents, .and(.contains(".plugin("), .contains("targets: [\"MyBuildToolPlugin\"]")))
             XCTAssertMatch(manifestContents, .and(.contains(".plugin("), .contains("capability: .buildTool()")))
 
-            let source = path.appending("Plugins", "MyBuildToolPlugin", "plugin.swift")
+            let source = path.appending("Plugins", "MyBuildToolPlugin.swift")
             XCTAssertFileExists(source)
             let sourceContents: String = try localFileSystem.readFileContents(source)
             XCTAssertMatch(sourceContents, .contains("struct MyBuildToolPlugin: BuildToolPlugin"))