In Morphir serialization format encode annotations as a Graph

[DamianReeves]

Morphir has the Graph type which is more or less a lightweight representation of an RDF Dataset/Graph.

My thought is that we should store a Graph as the value of the annotation when serializing the Morphir IR. This allows for us to have an RDF like mechanism for capturing meaningful metadata.

[TODO: Will expand on this later, wanted to capture the idea first]