Showing TCP connections in the I/O graph

## Feature Request

### What problem are you trying to solve?
As operator and developer, I want to have a visual overview of which pods are communicating. This doesn't only include HTTP requests, but long-running TCP connections, too.

### How should the problem be solved?
Currently linkerd's UI shows a graph of incoming and outgoing HTTP communications, but not non-HTTP TCP connections. These connections are only visible in the edges section. So users can't simply look in the graph but must iterate over all entries in the edge section. Additional to that, the missing visualization of connections in the graph could and do lead to sceptical looks. The question arises, if the connections are really working as inteded.

So for a better overview, less questions and faster debugging, the TCP connections should be displayed in the graph, too.

As you can see in the image, the edges section informs the user, that there is a connection from kafka to the zookeeper statefulset. This connection is missing in the graph above.

### How would users interact with this feature?
Users wouldn't manipulate any data. The view is "only" for visualization purposes, so that ops, devs, and devops can maintain, debug and check connections, without the need to iterate over a list of edge entries.

The issue does not name files, tests, or entry points. Start by comparing the existing UI graph with the edges section's TCP connection data; done means non-HTTP TCP connections appear in the graph while existing HTTP visualization remains correct.

Written by the indexing model from the issue text.