Event Lineage: Create Graph from Cluster Resources

[Cali0707]

Problem
We should use the constructor functions for the event lineage graph to construct the graph from actual graph resources. To do this, we should use the appropriate listers to list all the resources, and then construct the graph. Specificall, we should try and add all knative "vertices" first. So, brokers and channels should be added first, followed by types with edges such as eventtypes, triggers, and subscriptions.

Persona:
Which persona is this feature for?

Exit Criteria
An e2e test where a graph is constructed using live cluster resources

Time Estimate (optional):
How many developer-days do you think this may take to resolve? 2

Additional context (optional)
Add any other context about the feature request here.

[Cali0707]

/assign