[core] Allow overriding map metaserver URL and reset downloader cache

- Add custom meta server API.
- Implement override.
- Add reset hook and implement reset.
- Expose reset from Storage.
- Let JNI set URL and reset cache.

Signed-off-by: NoelClick <dev@noel.click>

android/sdk/src/main/cpp/app/organicmaps/sdk/Framework.cpp

@@ -1505,6 +1505,22 @@ JNIEXPORT void JNICALL Java_app_organicmaps_sdk_Framework_nativeGet3dMode(JNIEnv
   env->SetBooleanField(result, buildingsField, buildings);
 }
 
+JNIEXPORT void JNICALL Java_app_organicmaps_sdk_Framework_nativeSetCustomMapDownloadUrl(JNIEnv * env, jclass, 
+                                                                                        jstring url)
+{
+  std::string const nativeUrl = jni::ToNativeString(env, url);
+  GetPlatform().SetCustomMetaServerUrl(nativeUrl);
+
+  if (g_framework)
+  {
+    frm()->GetStorage().ResetMapDownloadMetaConfig();
+  }
+  else
+  {
+    LOG(LINFO, ("nativeSetCustomMapDownloadUrl: framework not created yet, skipping ResetMapDownloadMetaConfig"));
+  }
+}
+
 JNIEXPORT void JNICALL Java_app_organicmaps_sdk_Framework_nativeSetAutoZoomEnabled(JNIEnv * env, jclass,
                                                                                    jboolean enabled)
 {