Implement canonical formatter (#1107)

CLI commands also added: `pkl format check` and `pkl format apply`.

pkl-formatter/pkl-formatter.gradle.kts

@@ -0,0 +1,48 @@
+/*
+ * Copyright © 2025 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.
+ */
+plugins {
+  pklAllProjects
+  pklKotlinLibrary
+  pklPublishLibrary
+}
+
+dependencies {
+  api(projects.pklParser)
+
+  testImplementation(projects.pklCommonsTest)
+}
+
+tasks.test {
+  inputs
+    .dir("src/test/files/FormatterSnippetTests/input")
+    .withPropertyName("formatterSnippetTestsInput")
+    .withPathSensitivity(PathSensitivity.RELATIVE)
+  inputs
+    .dir("src/test/files/FormatterSnippetTests/output")
+    .withPropertyName("formatterSnippetTestsOutput")
+    .withPathSensitivity(PathSensitivity.RELATIVE)
+}
+
+publishing {
+  publications {
+    named<MavenPublication>("library") {
+      pom {
+        url.set("https://github.com/apple/pkl/tree/main/pkl-formatter")
+        description.set("Formatter for Pkl")
+      }
+    }
+  }
+}