test: add empty test classes for BankAccount concurrency and deadlock scenarios

src/test/java/banking/TestA.java

@@ -0,0 +1,4 @@
+package banking;
+
+public class TestA {
+}

src/test/java/banking/TestB.java

@@ -0,0 +1,4 @@
+package banking;
+
+public class TestB {
+}

src/test/java/banking/TestC.java

@@ -0,0 +1,4 @@
+package banking;
+
+public class TestC {
+}