Connectivity: Display robot "reachability" in list and robot settings page

[mcous]

overview

Post #2090, the app can now divide robots it knows about into three groups:

• Robot we've seen before and we don't know if its reachable
• Robot we've seen before and is not currently reachable
• Robot we've seen before and is currently reachable

As a user, I would like to know about the reachability of my robot(s) so that I:

• Don't attempt to do stuff with a robot that's not reachable
• Can take some action if a robot I expect to be reachable is not
• Can be confident that trying to interact with a "reachable" robot will not error out

(In this context, "reachable" means the robot successfully responds to a GET /health request).

current behavior

• Pre-2090: robots in list may be reachable or unreachable, without a clear way to know without recognizing that all attempts to connect fail
• Post-2090: only reachable robots are displayed in the list

acceptance criteria

• Reachable robots displayed in robot list
• Unreachable robots displayed in robot list
  • Should be visually distinct from reachable robots
• Settings page for an unreachable make sense. Some possibilities that come to mind:
  1. Settings page is not available for the user to navigate to
     • This option isn't optimal, because certain actions (e.g. robot software update) may be possible even if the full API application is unable to launch
  2. Or shows something similar to regular settings page with elements disabled
• Not sure what to do with unreachable robots
  • "Unknown" is a temporary state; the app will resolve to a known status within ~15 seconds
  • Could display them with a "?" or something
  • Could also just hide them

potential future work / tickets

• Ability to remove an unreachable robot from the list
• Ability to manually add a robot at a specific IP address to the list
  • We have users on networks that do not support mDNS
  • In these networks, the app cannot auto-populate the list

[mcous]

Closing this broad ticket in favor of feature milestone: https://github.com/Opentrons/opentrons/milestone/68