Draft: API: remove UniqueResult, lower-case at, size for ResultSet

Summary

• Remove UniqueResult
• At and Size are lower-case now (ResultSet, MultiResultSet)

include/caosdb/entity.h

@@ -338,7 +338,7 @@ public:
   /**
    * Return the current size of the properties container.
    *
-   * This is also the number of properties the owningn entity currently has.
+   * This is also the number of properties the owning entity currently has.
    */
   [[nodiscard]] inline auto Size() const -> int { return wrapped->size(); }
   /**