Show all nodes returned by korrel8r with visual indication for nodes that don't have working links.

[alanconway]

Currently the panel filters out nodes that are not clickable due to:

• missing optional plugins (e.g. netobserv)
• nodes that have no equivalent console screen (yet)
• link translations that are possible but not yet written

This causes disconnected graphs if the missing nodes are part of a path between visible nodes.

Nodes that are not clickable should be displayed with a visible indication such as:

• distinct colour (e.g. grey) or with some other visual effect.
• tooltip information e.g. "netobserv plugin is required to display this node"

Need UI input on the correct approach.

[alanconway]

The fix to #38 removes 404 errors but does not address missing missing link translations or visual presentation.

[alanconway]

@fkargbo please comment on the right way to present this visually.

[fkargbo]

@alanconway Let's review this to understand the use case/s for better UX assessment. Thanks

[alanconway]

@PeterYurkovich I'm working on displaying all the nodes - I can't assign issues in this repo.

[zhuje]

/assign @alanconway