Replace everrest based Websocket calls with new RPC framework.

The goal is to dismiss Everrest mechanism which opens Websocket channel to output long-lived async calls and use new JSON-RPC on top of Websockets instead (the one we currently use for FS Watchers and Exec agent).

This should be applied to every side of a triage: client-machine-master. Proposed tactic is following:

• Add it to the master side and use for IDE-Master connection. The goal - to clean IDE removing Master Message Bus entities and prepare removing Everrest WS (EWS) components from the Master.
  • #4275 - Rework client for Project service in order to avoid using Everrest based Websocket calls - DONE
• (may be performed in parallel with 1) Do the same for Machine (Agent) - IDE connection, remove Machine Message Bus from IDE (according to priority)
  • #4591 - Switch project importing output to the websocket JSON-RPC API endpoint - DONE
  • #4593 - Switch Debugger functionality to the websocket JSON-RPC API endpoint - DONE
  • #5346 - Rework client for Git service to avoid using Everrest based Websocket calls - DONE
  • #5349 - Rework Java plugin to avoid using Everrest based Websocket calls - DONE
  • #5350 - Rework Maven plugin to avoid using Everrest based Websocket calls - DONE
  • #5351 - Rework Testing plugin to avoid using Everrest based Websocket calls - DONE
  • #5348 - Rework Composer plugin to avoid using Everrest based Websocket calls - DONE
  • #5352 - Rework importing a project while consuming Factory to avoid using Everrest based Websocket calls - 2d - DONE
  • #5522 - Rework Navigate to File feature to avoid using Everrest based Websocket calls - DONE
  • #5523 - Rework Find Usages feature to avoid using Everrest based Websocket calls - DONE
  • #5524 - Rework Language Server plugin to avoid using Everrest based Websocket calls - CANCELLED
• (depends on 1) Declare EWS mechanism/components as deprecated, apply new implementation for UD - Master connection and remove EWS using there in 4 weeks.
  • https://github.com/eclipse/che/issues/4763 - [dashboard] Use JSON RPC instead websocket requests on master API - ANALYZING
• (depends on 2) same as 3 for Machine (Ws-Agent).
  • https://github.com/eclipse/che/issues/5358 - [dashboard] Use JSON-RPC instead websocket requests on workspace agent API - ANALYZING
• Remove EWS from workspace master in SPI branch
  • https://github.com/eclipse/che/issues/5357 - Clean workspace master of EWS - ANALYZING
• Rework CLI to avoid using Everrest based Websocket calls #5841

[azatsarynnyy]

I’ve added three more tasks (#5522, #5523, #5524) to this epic since several features which use Everrest based Websocket calls were found recently.

[vparfonov]

@benoitf Can you take a look https://github.com/eclipse/che/issues/5841? Looks like you are best person for it.