Add summaries and groups to gradle tasks

Fixes and closes apple#188 by adding task names and groups to
major Pkl Gradle Plugin tasks

Signed-off-by: Sam Gammon <sam@elide.ventures>

pkl-gradle/src/main/java/org/pkl/gradle/PklPlugin.java

@@ -171,6 +171,8 @@ private void configureJavaCodeGenTasks(NamedDomainObjectContainer<JavaCodeGenSpe
           createModulesTask(JavaCodeGenTask.class, spec)
               .configure(
                   task -> {
+                    task.setDescription(TaskConstants.GENERATE_JAVA_DESCRIPTION);
+                    task.setGroup(TaskConstants.TASK_GROUP_CODEGEN);
                     configureCodeGenTask(task, spec);
                     task.getGenerateGetters().set(spec.getGenerateGetters());
                     task.getGenerateJavadoc().set(spec.getGenerateJavadoc());
@@ -200,6 +202,8 @@ private void configureKotlinCodeGenTasks(NamedDomainObjectContainer<KotlinCodeGe
           createModulesTask(KotlinCodeGenTask.class, spec)
               .configure(
                   task -> {
+                    task.setDescription(TaskConstants.GENERATE_KOTLIN_DESCRIPTION);
+                    task.setGroup(TaskConstants.TASK_GROUP_CODEGEN);
                     configureCodeGenTask(task, spec);
                     task.getGenerateKdoc().set(spec.getGenerateKdoc());
                   });
@@ -228,7 +232,12 @@ private void configurePkldocTasks(NamedDomainObjectContainer<PkldocSpec> specs)
                       .map(it -> it.dir("pkldoc").dir(spec.getName())));
 
           createModulesTask(PkldocTask.class, spec)
-              .configure(task -> task.getOutputDir().set(spec.getOutputDir()));
+              .configure(
+                  task -> {
+                    task.setDescription(TaskConstants.GENERATE_PKLDOC_DESCRIPTION);
+                    task.setGroup(TaskConstants.TASK_GROUP_DOCS);
+                    task.getOutputDir().set(spec.getOutputDir());
+                  });
         });
   }
 
@@ -242,6 +251,8 @@ private void configureTestTasks(NamedDomainObjectContainer<TestSpec> specs) {
           var testTask = createModulesTask(TestTask.class, spec);
           testTask.configure(
               task -> {
+                task.setDescription(TaskConstants.GENERATE_PKLDOC_DESCRIPTION);
+                task.setGroup(TaskConstants.TASK_GROUP_DOCS);
                 task.getJunitReportsDir().set(spec.getJunitReportsDir());
                 task.getOverwrite().set(spec.getOverwrite());
               });

pkl-gradle/src/main/java/org/pkl/gradle/TaskConstants.java

@@ -0,0 +1,38 @@
+/**
+ * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pkl.gradle;
+
+/** Constant values used by tasks */
+class TaskConstants {
+  private TaskConstants() {
+    /* no construction */
+  }
+
+  /** Gradle task group declared for code-gen tasks. */
+  static final String TASK_GROUP_CODEGEN = "Code generation";
+
+  /** Gradle task group declared for documentation tasks. */
+  static final String TASK_GROUP_DOCS = "Documentation";
+
+  /** Gradle task description for generating Java code from Pkl modules. */
+  static final String GENERATE_JAVA_DESCRIPTION = "Generate Java code from Pkl modules";
+
+  /** Gradle task description for generating Kotlin code from Pkl modules. */
+  static final String GENERATE_KOTLIN_DESCRIPTION = "Generate Kotlin code from Pkl modules";
+
+  /** Gradle task description for generating Pkldoc from Pkl modules. */
+  static final String GENERATE_PKLDOC_DESCRIPTION = "Generate Pkldoc from Pkl modules";
+}