Feat: Support ahead of time input-added event about subgraph

[brunomenezes]

I am implementing this in the same branch for issue #8

[tuler]

Why do you think we need the property indicating the source of creation? We could just let the fields that we don’t know how to fill blank and filled up later

[brunomenezes]

Why do you think we need the property indicating the source of creation? We could just let the fields that we don’t know how to fill blank and filled up later

The only field we don't know is the factory address; all the rest are set with default values. I'm unsure if you are talking about adding the status field, but my rationale is to work with explicit intent rather than the opaque null here and there.