dotty phase 2: scalafix ExplicitNonNullaryApply (#28949)

* scalafix ExplicitNonNullaryApply prepare

+ Temporarily use com.sandinh:sbt-scalafix because scalacenter/scalafix#1098
+ Add ExplicitNonNullaryApply rule to .scalafix.conf
+ Manually fix a NonNullaryApply case in DeathWatchSpec that cause
  `fixall` fail because ExplicitNonNullaryApply rule incorrectly rewrite
  `context unbecome` to `context unbecome()` instead of `context.unbecome()`

* scalafix ExplicitNonNullaryApply

fix by enabling only ExplicitNonNullaryApply rule in .scalafix.conf then:
```
% sbt -Dakka.build.scalaVersion=2.13.1
> fixall
```

* scalafmtAll

* Revert to ch.epfl.scala:sbt-scalafix

Co-authored-by: Bùi Việt Thành <thanhbv@sandinh.net>

akka-distributed-data/src/test/scala/akka/cluster/ddata/LotsOfDataBot.scala

@@ -57,7 +57,7 @@ object LotsOfDataBot {
       // Create an Akka system
       val system = ActorSystem("ClusterSystem", config)
       // Create an actor that handles cluster domain events
-      system.actorOf(Props[LotsOfDataBot], name = "dataBot")
+      system.actorOf(Props[LotsOfDataBot](), name = "dataBot")
     }
   }