Align the logging format of the IosLoggerBackend with the XLogger.

Replaces the logging handler with a handler that supports the same format as the XLogger. Otherwise only the raw string is logged to console.

PiperOrigin-RevId: 591315434

Author: j2objc-copybara

jre_emul/Classes/com/google/j2objc/util/logging/IOSLogHandler.java

@@ -122,7 +122,11 @@ public String format(LogRecord record) {
   private Object nativeLog;
 
   public IOSLogHandler() {
-    setFormatter(new IOSLogFormatter());
+    this(new IOSLogFormatter());
+  }
+
+  public IOSLogHandler(Formatter customFormatter) {
+    setFormatter(customFormatter);
   }
 
   @Override