[dashboard-next] show warning banner when websockets are not available

[sleshchenko]

Is your enhancement related to a problem? Please describe.

That's already done for the existing dashboard.
Dashboard next should show warning banner when websockets are not available since it leads to
incorrect work.

The related issue and PR for Dashboard #17280 eclipse-che/che-dashboard#72

[sleshchenko]

@ParvathyRV will provide the design
Spoiler: PF banner should be used here https://www.patternfly.org/v4/components/banner/

[parvathyvr]

@sleshchenko -below is the mock up screen using the PF4 banner for a global alert scenario.

[sleshchenko]

The described issue is fully solved by referenced PRs (not all are merged): warning banner is shown when Dashboard is loaded but websockets are blocked.

But it makes sense to extend the scope a bit:

• websocket context should be on WorkspaceClient side and clients (like dashboard does not need to define it). I think it may be a legacy from times when we had minor and major websocket endpoints Clean up branding che-incubator/che-dashboard-next#112 (comment)
• client should be able to define a token initially, and then redefine it once it's expired Modify the incoming request auth header to use the new bearer token che-incubator/che-dashboard-next#110 (review)

Then we'll get the following workflow:

• WebSocket is established.
• WebSocket is interrupted.
  • WsClient notifies the dashboard about it.
  • Dashboard displays banner that WebSocket is lost
• WsClient endless tries to reconnect with dynamic delay: first 10 times every second, then every 30 seconds for example.
• Once Websocket is reestablished, WSClient notifies Dashboard that everything is fine with Websockets now.
• Dashboard hides the banner.

[sleshchenko]

Seems every related PR is merged. @JPinkney Can this issue be closed or there is anything left?

[JPinkney]

It can be closed