Use nestedName for getting the name of an API

This changes the Java `CallableMethod.getApiName()` to use `nestedName`
instead of `getSourceDeclaration`. `getSourceDeclaration` would return a
`RefType`, on which the `toString()` method returns its `getName`().
However, for nested types this wouldn't work and wouldn't include the
enclosing type. This fixes it by using `nestedName` which matches the
method that is also used for determining whether a type matches an
extensible predicate.

extensions/ql-vscode/src/data-extensions-editor/queries/java.ts

@@ -81,7 +81,7 @@ class CallableMethod extends Method {
    */
   string getApiName() {
     result =
-      this.getDeclaringType().getPackage() + "." + this.getDeclaringType().getSourceDeclaration() +
+      this.getDeclaringType().getPackage() + "." + this.getDeclaringType().nestedName() +
         "#" + this.getName() + paramsString(this)
   }