Initial support of annotation loading at runtime

In order to locate an annotated entity, we need to implement almost the whole
Java element model (which will be used anyway for Java descriptor loading)

compiler/testData/loadJava/compiledJava/annotations/StringConstantInParam.java

@@ -1,3 +1,5 @@
+// SKIP_IN_RUNTIME_TEST because there's no stable way to determine if a field is initialized with a non-null value in runtime
+
 package test;
 
 public interface StringConstantInParam {