Expose next_event_async in bindings

.. which requires us to include a dependency on the `kotlinx-coroutines`
package.

Author: tnull

bindings/kotlin/ldk-node-android/lib/build.gradle.kts

@@ -43,6 +43,7 @@ android {
 dependencies {
     implementation("net.java.dev.jna:jna:5.12.0@aar")
     implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk7")
+    implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.6.4")
     implementation("androidx.appcompat:appcompat:1.4.0")
     implementation("androidx.core:core-ktx:1.7.0")
     api("org.slf4j:slf4j-api:1.7.30")

bindings/kotlin/ldk-node-jvm/lib/build.gradle.kts

@@ -46,6 +46,7 @@ dependencies {
 
     // Use the Kotlin JDK 8 standard library.
     implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
+    implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.6.4")
 
     implementation("net.java.dev.jna:jna:5.12.0")
 }

bindings/ldk_node.udl

@@ -43,6 +43,8 @@ interface LDKNode {
 	void stop();
 	Event? next_event();
 	Event wait_next_event();
+	[Async]
+	Event next_event_async();
 	void event_handled();
 	PublicKey node_id();
 	sequence<SocketAddress>? listening_addresses();