SystemSwitch does not replicate World behavior when calling a non-root System from a root one

[qbzzt]

When we call a System that is not in the root namespace, we expect it to be a call and run under the System's address.

However, when we use SystemSwitch to call from a root System, it always uses delegatecall. This results in confusing behavior, for example that you need to put ERC-20 tokens to be distributed by the non root System on the World address.