Add Interface.isLocal and use it where appropriate

Some EJB logic regrettably needs to be renamed out of the way. Hopefully the churn caused by this is less than would be caused if Interface's isLocal needed to be named differently from Class.isLocal.

java/ql/lib/semmle/code/java/Statement.qll

@@ -786,14 +786,20 @@ class LocalVariableDeclStmt extends Stmt, @localvariabledeclstmt {
   override string getAPrimaryQlClass() { result = "LocalVariableDeclStmt" }
 }
 
-/** A statement that declares a local class. */
+/** A statement that declares a local class or interface. */
 class LocalClassDeclStmt extends Stmt, @localclassdeclstmt {
   /** Gets the local class declared by this statement. */
-  LocalClass getLocalClass() { isLocalClass(result, this) }
+  LocalClassOrInterface getLocalClass() { isLocalClass(result, this) }
 
-  override string pp() { result = "class " + this.getLocalClass().toString() }
+  private string getDeclKeyword() {
+    result = "class" and this.getLocalClass() instanceof Class
+    or
+    result = "interface" and this.getLocalClass() instanceof Interface
+  }
 
-  override string toString() { result = "class ..." }
+  override string pp() { result = this.getDeclKeyword() + " " + this.getLocalClass().toString() }
+
+  override string toString() { result = this.getDeclKeyword() + " ..." }
 
   override string getHalsteadID() { result = "LocalClassDeclStmt" }