Merge outgoing links for newcomer sub URLS of a domain which already exists in the current graph

Currently, for example if a new URL **x** `https://www.instagram.com/astarwth/?hl=en` is discovered and we already have **y** `https://www.instagram.com/kanyewest/?hl=en` in the current graph, the newly discovered URL won't add any new value to the graph, since **x** and **y** are considered the same.

Correct & expected behavior is merging (set union of) the outgoing links of **x** and **y**.