Light Node Feature

[sandrask]

As per spec:

Light Node: A node that downloads and processes only Anchor Files and Map Files on a proactive basis, waiting until resolution time to download and process the Chunk File related to a given DID. This type of configuration enables a node to operate trustlessly while consuming approximately one order of magnitude less storage.

Currently we don't have configuration or implementation to operate in Light Node mode - we probably don't even have need for it at all (@troyronda)