Build tool plugins arent called on windows < 6.0

Author: plemarquand

assets/test/targets/Plugins/BuildToolPlugin/BuildToolPlugin.swift

@@ -6,6 +6,11 @@ struct SimpleBuildToolPlugin: BuildToolPlugin {
     func createBuildCommands(context: PluginContext, target: Target) async throws -> [Command] {
         guard let sourceFiles = target.sourceModule?.sourceFiles else { return [] }
 
+        // Build tool plugins are not being called on Windows with Swift < 6.0.
+        #if os(Windows) && swift(<6.0)
+        return []
+        #endif
+
         let generatorTool = try context.tool(named: "ExecutableTarget")
 
         // Construct a build command for each source file with a particular suffix.

test/integration-tests/ui/ProjectPanelProvider.test.ts

@@ -129,7 +129,14 @@ suite("ProjectPanelProvider Test Suite", function () {
             );
         });
 
-        test("Shows files generated by build tool plugin", async () => {
+        test("Shows files generated by build tool plugin", async function () {
+            if (
+                process.platform === "win32" &&
+                workspaceContext.globalToolchain.swiftVersion.isLessThan(new Version(6, 0, 0))
+            ) {
+                this.skip();
+            }
+
             const children = await getHeaderChildren("Targets");
             const target = children.find(n => n.name === "LibraryTarget") as PackageNode;
             expect(