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/main/scala/akka/cluster/ddata/DurableStore.scala

@@ -166,7 +166,7 @@ final class LmdbDurableStore(config: Config) extends Actor with ActorLogging {
     val valueBuffer = lmdb().valueBuffer
     if (valueBuffer.remaining < size) {
       DirectByteBufferPool.tryCleanDirectByteBuffer(valueBuffer)
-      _lmdb = OptionVal.Some(lmdb.copy(valueBuffer = ByteBuffer.allocateDirect(size * 2)))
+      _lmdb = OptionVal.Some(lmdb().copy(valueBuffer = ByteBuffer.allocateDirect(size * 2)))
     }
   }
 

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

@@ -64,8 +64,8 @@ class LocalConcurrencySpec(_system: ActorSystem)
   "Updates from same node" must {
 
     "be possible to do from two actors" in {
-      val updater1 = system.actorOf(Props[Updater], "updater1")
-      val updater2 = system.actorOf(Props[Updater], "updater2")
+      val updater1 = system.actorOf(Props[Updater](), "updater1")
+      val updater2 = system.actorOf(Props[Updater](), "updater2")
 
       val numMessages = 100
       for (n <- 1 to numMessages) {

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")
     }
   }