Improve milestone filter on issues page (#22423)

Now we have `All milestones`, `No milestones`, `Open milestones` and
`Closed milestones`.
Fix #11924
Fix #22411 

<img width="1166" alt="image"
src="https://user-images.githubusercontent.com/81045/212243375-95eea035-a972-44b8-8088-53db614cb07e.png">

models/db/search.go

@@ -31,5 +31,5 @@ const (
 const (
 	// Which means a condition to filter the records which don't match any id.
 	// It's different from zero which means the condition could be ignored.
-	NoneID = -1
+	NoConditionID = -1
 )