Implement tests to sam-with-receiver support in new scripting API

plus minor tests refactoring

libraries/scripting/jvm-host-test/testData/samWithReceiver/Exec.java

@@ -0,0 +1,3 @@
+public class Exec {
+    void exec(Sam sam) {}
+}

libraries/scripting/jvm-host-test/testData/samWithReceiver/Sam.java

@@ -0,0 +1,4 @@
+@SamWithReceiver1
+public interface Sam {
+    void run(String a);
+}

libraries/scripting/jvm-host-test/testData/samWithReceiver/SamWithReceiver1.java

@@ -0,0 +1,6 @@
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+@Retention(RetentionPolicy.RUNTIME)
+public @interface SamWithReceiver1 {
+}

libraries/scripting/jvm-host-test/testData/samWithReceiver/test.samwr.kts

@@ -0,0 +1,5 @@
+val e = Exec()
+
+e.exec {
+    this.substring(1)
+}