Don't error when attempting to sort on an object field (#4806)

* add failing test to demonstrate that you can't sort on a
field in an object.

* Only validate the base of the field name.

* fix test name

* Only test sort for mongo.

* pg order by nested object

* level 2 test

* Factor out operation to get a field's base name.  Add comment.

* tweak comment wording so it wont make my grammar teacher angry.

src/Adapters/Storage/Postgres/PostgresStorageAdapter.js

@@ -1397,11 +1397,12 @@ export class PostgresStorageAdapter implements StorageAdapter {
     if (sort) {
       const sortCopy: any = sort;
       const sorting = Object.keys(sort).map((key) => {
+        const transformKey = transformDotFieldToComponents(key).join('->');
         // Using $idx pattern gives:  non-integer constant in ORDER BY
         if (sortCopy[key] === 1) {
-          return `"${key}" ASC`;
+          return `${transformKey} ASC`;
         }
-        return `"${key}" DESC`;
+        return `${transformKey} DESC`;
       }).join();
       sortPattern = sort !== undefined && Object.keys(sort).length > 0 ? `ORDER BY ${sorting}` : '';
     }