Improve displaying of Agents table in Summary page

[antoninbas]

The Summary page displays a table of all Antrea Agents in the K8s cluster. For a large cluster, with potentially 100+ Nodes, the list can be quite large.

We should improve this:

• we should display a bounded number of Antrea Agents (e.g., up to 10), with pagination support
• the table should be sortable by columns
• the table should be sortable by name, to quickly find a specific Agent

For reference, this is what the page looks like at the moment:

[antoninbas]

At the moment, I would suggest handling this entirely in the frontend, with no API change.