Rename use-before-declare test cases

semantic/usage_before_declaration_field.java → semantic/use_before_declare_field.java

-class UsageBeforeDeclarationField {
+class UseBeforeDeclareField {
     public static void main(String[] args) {
-        UsageBeforeDeclarationField x = new UsageBeforeDeclarationField();
+        UseBeforeDeclareField x = new UseBeforeDeclareField();
         x.test();
     }
 

semantic/usage_before_declaration_method.java → semantic/use_before_declare_method.java

-class UsageBeforeDeclarationMethod {
+class UseBeforeDeclareMethod {
     public static void main(String[] args) {}
 
     public void methodA() {