Cleanup implementation of REST views

- specify return type if possible
- remove unnecessary throw declarations
- convert some of the thrown exceptions to RestExceptions
- do not throw Exception but specific exceptions
- sort throw declarations (first RestExceptions, then other
  exceptions)

Having explicit return types and exceptions makes it easier to
programatically invoke the REST views, e.g. if a plugin wants to add a
REST view that wraps a Gerrit core REST view.

Change-Id: I5c59553b6cfad457f7ec037cceb08936247bf8e8
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>

gerrit-server/src/main/java/com/google/gerrit/server/change/GetRelated.java

@@ -70,7 +70,7 @@ public class GetRelated implements RestReadView<RevisionResource> {
   }
 
   @Override
-  public Object apply(RevisionResource rsrc)
+  public RelatedInfo apply(RevisionResource rsrc)
       throws RepositoryNotFoundException, IOException, OrmException {
     Repository git = gitMgr.openRepository(rsrc.getChange().getProject());
     try {