feat: add isChanged() to avoid rewriting unchanged files.

This is important because the rewritten() method will trim whitespace even if it does nothing else, which we want to avoid.

recipes/dependencies/src/main/kotlin/cash/recipes/dependencies/DependenciesSimplifier.kt

@@ -33,8 +33,11 @@ public class DependenciesSimplifier private constructor(
   private val terminalNewlines = Whitespace.countTerminalNewlines(tokens)
   private val dependencyExtractor = DependencyExtractor(input, tokens, indent)
 
+  private var changes = false
   private var isInBuildscriptBlock = false
 
+  public fun isChanged(): Boolean = changes
+
   @Throws(KotlinParseException::class)
   public fun rewritten(): String {
     errorListener.getErrorMessages().ifNotEmpty {
@@ -76,6 +79,7 @@ public class DependenciesSimplifier private constructor(
         val newText = simplify(declaration)
 
         if (newText != null) {
+          changes = true
           rewriter.replace(elementCtx.start, getStop(elementCtx), newText)
         }
       }