Motivation

The main reason for this PR is to use the latest "pluggable monitor" gRPC APIs #769. But in order to use the new APIs, we needed to refactor all the Serial Monitor architecture. All this work allowed us to solve a number of issues that weren't impossible or too expensive to solve before the change, and we also took advantage of this effort to implement a more solid architecture.

This PR solves:

• Upload fails if port is open in Serial Monitor of another window #586
• Use the latest "pluggable monitor" gRPC APIs #769
• Serial Monitor/Plotter don't use per-window port selection #613

Change description

The architecture has been redesigned like this:
image

Call Stack / Event Flow when opening Serial monitor or Plotter

Numbers correspond to those in the diagram above.

1. A monitor is opened (monitor-widget or plotter-frontend-contribution) from the IDE;
2. monitor-widget or plotter-frontend-contribution invokes .startMonitor() method on monitor-manager-proxy-client-impl from .onBeforeAttach() or .startPlotter(), respectively;
3. monitor-manager-proxy-client-impl.startMonitor() invokes .startMonitor() method on monitor-manager-proxy-impl;
4. monitor-manager-proxy-impl.startMonitor() invokes .startMonitor() method on monitor-manager;
5. monitor-manager creates a monitor-service from monitor-service-factory if not existing, injecting monitor-settings-provider-impl and web-socket-provider-impl;
6. monitor-manager invokes .start() method on created/existing monitor-service;
   • this creates a duplex stream (gRPC) to communicate with our CLI;
   • An injected WebSocket server is instantiated here;
7. The result from monitor-service.start() method is returned to the monitor-manager-proxy-impl when it's duplex connection is successfully connected (if no error);
8. monitor-manager-proxy-impl invokes .connect() on the monitor-manager-proxy-client-impl if value returned from monitor-service.start() method is Status.OK or Status.ALREADY_CONNECTED;
   • this creates a WebSocket client linked to the WebSocket server created for our monitor-service;

Reviewer checklist

• PR addresses a single concern.
• The PR has no duplicates (please search among the Pull Requests before creating one)
• PR title and description are properly filled.
• Docs have been added / updated (for bug fixes / features)