When the SymbolGraph json is requested via (key.retrieve_symbol_graph: 1) this adds
a new field in the response that lists all the parent contexts of the symbol under
the cursor with their symbol graph kind and name, and their USR:
key.parent_contexts: [
{
key.kind: "swift.struct",
key.name: "Parent",
key.usr: "s:27cursor_symbol_graph_parents6ParentV"
},
...
]
}
Resolves rdar://problem/73904365
