Require to tell if default to load a data/search attribute

[longquanzheng]

Today all the data/search attributes are loading by default.

This is wasteful if the state/RPC don't need to read some/any data/search attributes.

A better approach is to let user to define the data attributes with whether or not the attribute should be loaded by default. If not loading by default, then state/RPC will have to specifically select the attribute key to load