fix: add WithForeign attribute to LogWriter interface

With this attribute, the LogWriter trait can be implemented
on the foreign side, e.g. in Kotlin, the CustomLogWriter can
implement LogWriter directly.

Author: enigbe

bindings/kotlin/ldk-node-jvm/lib/src/test/kotlin/org/lightningdevkit/ldknode/LibraryTest.kt

@@ -93,8 +93,8 @@ fun waitForBlock(esploraEndpoint: String, blockHash: String) {
     }
 }
 
-class CustomLogWriter(private var currentLogLevel: LogLevel = LogLevel.INFO, noPointer: NoPointer = NoPointer) :
-    LogWriter(noPointer) {
+class CustomLogWriter(private var currentLogLevel: LogLevel = LogLevel.INFO) :
+    LogWriter {
     enum class LogLevel {
         ERROR, WARN, INFO, DEBUG, TRACE, GOSSIP
     }

bindings/ldk_node.udl

@@ -41,7 +41,7 @@ dictionary LogRecord {
 	u32 line;
 };
 
-[Trait]
+[Trait, WithForeign]
 interface LogWriter {
     void log(LogRecord record);
 };