Bringing back live Groot 2 monitoring

[ajtudela]

Hi everyone,

Last month I reintroduced Groot2 monitoring into Nav2, here.

I know that the free version limits live monitoring up to 20 nodes, but for all of us who had the paid version, being able to visualize the BT often saves us in a hurry. With the PRO version of Groot 2, the content of the blackboard can be visualized, allowing the introspection of the BT nodes.

I open this issue to see if there are people interested in this feature.