MM-48614: saves priority for drafts (#21752)

* MM-48614: saves priority for drafts

Adds a new column in the drafts table, "priority".
This way we can save post's priority in the draft.

Fixes OmitConnectionId, which when you published a ws event for a user
was getting bypassed.

Fixes Get for drafts returns deleted ones as well, which is needed for
upsert.

* Adds test case for the OmitConnectionId

* Addresses review comments, removes DeleteAt

* Vets

* Adds missing translation

* Re-instates DeleteAt column

* Adds separate case to get draft including deleted

* Fixes Update Draft

* Empty

model/websocket_message_test.go

@@ -215,9 +215,10 @@ func TestWebSocketEventDeepCopy(t *testing.T) {
 		TeamId:                "ccc",
 		ContainsSanitizedData: true,
 		ContainsSensitiveData: true,
+		OmitConnectionId:      "ddd",
 	}
 
-	ev := NewWebSocketEvent("test", "team", "channel", "user", omitUsers, "")
+	ev := NewWebSocketEvent("test", "team", "channel", "user", omitUsers, "ddd")
 
 	ev.Add("post", &Post{})
 	ev.SetBroadcast(broadcast)