Provide daemon progress/log feedback for restarts

[DanTup]

In Flutter, restarts provide two sets of feedback to the user during a restart/reload:

[10:39:38 AM]: ==> [{"id":"1","method":"app.restart","params":{"appId":"3c6c4df9-d128-4ff5-81ee-9cdd5ce06ad0","fullRestart":true,"pause":true,"reason":"manual"}}]
[10:39:38 AM]: <== [{"event":"app.progress","params":{"appId":"3c6c4df9-d128-4ff5-81ee-9cdd5ce06ad0","id":"2","progressId":"hot.restart","message":"Performing hot restart..."}}]
[10:39:38 AM]: <== [{"event":"app.progress","params":{"appId":"3c6c4df9-d128-4ff5-81ee-9cdd5ce06ad0","id":"3","progressId":null,"message":"Syncing files to device iPhone XS Max..."}}]
[10:39:39 AM]: <== [{"event":"app.progress","params":{"appId":"3c6c4df9-d128-4ff5-81ee-9cdd5ce06ad0","id":"3","progressId":null,"finished":true}}]
[10:39:39 AM]: <== [{"event":"app.progress","params":{"appId":"3c6c4df9-d128-4ff5-81ee-9cdd5ce06ad0","id":"2","progressId":"hot.restart","finished":true}}]
[10:39:39 AM]: <== Restarted application in 1,332ms.
[10:39:39 AM]: <== [{"id":"1","result":{"code":0,"message":""}}]

There are app.progress events (which in VS Code, we'll use to show a progress notification), and also there's a message printed to stdout (Restarted application in 1,332ms.). Both of these are useful - one gives a good indication that something is happening to the user, and the other gives confirmation that something actually happened (eg. if you missed the notification).

The webdev daemon doesn't currently produce either of these:

[10:41:08 AM]: ==> [{"id":"1","method":"app.restart","params":{"appId":"ip4xnl9lCXJbpW74KfYlGw==","fullRestart":true,"pause":false,"reason":"manual"}}]
[10:41:08 AM]: <== [{"id":"1","result":{"code":0,"message":"[Success type: Success]"}}]

Which means the operation is completely silent. Is it possible to emit similar messages for webdev? (Using daemon.logMessage instead of writing non-JSON is fine by me, they go to the same place now).

[DanTup]

@grouma There were two parts to this - the app.progress events, and also this:

[10:39:39 AM]: <== Restarted application in 1,332ms.

This one comes via stdout in Flutter, but I think using daemon.logMessage would be fine. This one persists on the users screen (in the Debug Console) whereas the progress one you can miss if it's fast. Could we add this too? (I think it's just a case of timing the restart call you have and sending it with daemon.logMessage).