Improve org.pkl.formatter.Formatter JVM API (#1428)

Makes for less fussing around to consume this API from the Gradle side

Author: HT154

buildSrc/src/main/kotlin/PklFormatterSpotless.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2025-2026 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.
@@ -47,20 +47,11 @@ class PklFormatterFunc(@Transient private val configuration: Configuration) :
 
   private val formatterClass by lazy { classLoader.loadClass("org.pkl.formatter.Formatter") }
 
-  private val grammarVersionClass by lazy {
-    classLoader.loadClass("org.pkl.formatter.GrammarVersion")
-  }
-
-  private val grammarVersionLatestMethod by lazy { grammarVersionClass.getMethod("latest") }
-
-  private val formatMethod by lazy {
-    formatterClass.getMethod("format", String::class.java, grammarVersionClass)
-  }
+  private val formatMethod by lazy { formatterClass.getMethod("format", String::class.java) }
 
   private val formatterInstance by lazy { formatterClass.getConstructor().newInstance() }
 
   override fun apply(input: String): String {
-    val latestGrammarVersion = grammarVersionLatestMethod(null)
-    return formatMethod(formatterInstance, input, latestGrammarVersion) as String
+    return formatMethod(formatterInstance, input) as String
   }
 }

pkl-formatter/src/main/kotlin/org/pkl/formatter/Formatter.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2025-2026 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.
@@ -31,6 +31,7 @@ class Formatter {
    * @return the formatted Pkl source code as a string
    * @throws java.io.IOException if the file cannot be read
    */
+  @JvmOverloads
   fun format(path: Path, grammarVersion: GrammarVersion = GrammarVersion.latest()): String {
     return format(Files.readString(path), grammarVersion)
   }
@@ -42,6 +43,7 @@ class Formatter {
    * @param grammarVersion grammar compatibility version
    * @return the formatted Pkl source code as a string
    */
+  @JvmOverloads
   fun format(text: String, grammarVersion: GrammarVersion = GrammarVersion.latest()): String {
     val parser = GenericParser()
     val builder = Builder(text, grammarVersion)
@@ -60,7 +62,6 @@ enum class GrammarVersion(val version: Int, val versionSpan: String) {
   V2(2, "0.30+");
 
   companion object {
-    @JvmStatic
-    fun latest(): GrammarVersion = entries.maxBy { it.version }
+    @JvmStatic fun latest(): GrammarVersion = entries.maxBy { it.version }
   }
 }