MM-22706: pass along set_online flag in websocket response (#14591)

* MM-22706: pass along set_online flag in websocket response

To let the client know whether a user has created a post without
being online or not, we get the set_online query param and
pass it down to the websocket event being passed down to the client.

With this PR, the "data" field of the `posted` event will contain
a `set_online` boolean field set to true/false depending on the
query_param set_online value set in the createPost call.

* Setting to false for auto responder

Co-authored-by: mattermod <mattermod@users.noreply.github.com>

app/plugin_test.go

@@ -663,7 +663,7 @@ func TestPluginPanicLogs(t *testing.T) {
 			Message:   "message_",
 			CreateAt:  model.GetMillis() - 10000,
 		}
-		_, err := th.App.CreatePost(post, th.BasicChannel, false)
+		_, err := th.App.CreatePost(post, th.BasicChannel, false, true)
 		assert.Nil(t, err)
 
 		testlib.AssertLog(t, th.LogBuffer, mlog.LevelDebug, "panic: some text from panic")