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)))
     }
   }