Add support for HTTP rewrites (#1062)

This adds a new configuration option for the HTTP client to replace URI prefixes when making outbound calls.

Follows the design of https://github.com/apple/pkl-evolution/pull/17

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

@@ -473,6 +473,7 @@ public class PklPlugin implements Plugin<Project> {
     task.getTestPort().set(spec.getTestPort());
     task.getHttpProxy().set(spec.getHttpProxy());
     task.getHttpNoProxy().set(spec.getHttpNoProxy());
+    task.getHttpRewrites().set(spec.getHttpRewrites());
   }
 
   private List<File> getTransitiveModules(AnalyzeImportsTask analyzeTask) {

pkl-gradle/src/main/java/org/pkl/gradle/spec/BasePklSpec.java

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 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.
@@ -57,4 +57,6 @@ public interface BasePklSpec {
   Property<URI> getHttpProxy();
 
   ListProperty<String> getHttpNoProxy();
+
+  MapProperty<URI, URI> getHttpRewrites();
 }

pkl-gradle/src/main/java/org/pkl/gradle/task/BasePklTask.java

@@ -142,6 +142,10 @@ public abstract class BasePklTask extends DefaultTask {
   @Optional
   public abstract ListProperty<String> getHttpNoProxy();
 
+  @Input
+  @Optional
+  public abstract MapProperty<URI, URI> getHttpRewrites();
+
   /**
    * There are issues with using native libraries in Gradle plugins. As a workaround for now, make
    * Truffle use an un-optimized runtime.
@@ -195,6 +199,7 @@ public abstract class BasePklTask extends DefaultTask {
               Collections.emptyList(),
               getHttpProxy().getOrNull(),
               getHttpNoProxy().getOrElse(List.of()),
+              getHttpRewrites().getOrNull(),
               Map.of(),
               Map.of());
     }

pkl-gradle/src/main/java/org/pkl/gradle/task/ModulesTask.java

@@ -163,6 +163,7 @@ public abstract class ModulesTask extends BasePklTask {
               Collections.emptyList(),
               null,
               List.of(),
+              getHttpRewrites().getOrNull(),
               Map.of(),
               Map.of());
     }