CliOptions: write info to console instead of err

Currently, info is written to out if out is not used for result output,
and to err otherwise.

Let's enhance this approach as follows: if out is not used, then we'll
write into to out, as before; otherwise, before resorting to err, check
if the console is available and use it then.

scalafmt-cli/src/main/scala/org/scalafmt/cli/CliOptions.scala

@@ -40,7 +40,9 @@ object CliOptions {
       if (parsed.quiet) Output.NoopStream
       else {
         val usesOut = parsed.stdIn || parsed.writeMode.usesOut
-        new Output.FromStream(
+        val cons = if (usesOut) System.console() else null
+        if (cons ne null) new Output.FromWriter(cons.writer())
+        else new Output.FromStream(
           if (parsed.noStdErr || !usesOut) parsed.common.out
           else parsed.common.err,
         )

scalafmt-cli/src/main/scala/org/scalafmt/cli/Output.scala

@@ -1,6 +1,7 @@
 package org.scalafmt.cli
 
 import java.io._
+import java.nio.charset._
 
 object Output {
 
@@ -29,4 +30,23 @@ object Output {
     override def printWriter: PrintWriter = new PrintWriter(obj)
   }
 
+  class FromWriter(val obj: Writer, charset: Charset = StandardCharsets.UTF_8)
+      extends OutputStream with StreamOrWriter {
+
+    override def write(b: Int): Unit = obj.write(b & 0xf)
+    override def write(b: Array[Byte]): Unit = obj.write(new String(b, charset))
+    override def write(b: Array[Byte], off: Int, len: Int): Unit = obj
+      .write(new String(b, off, len, charset))
+
+    override def flush(): Unit = obj.flush()
+    override def close(): Unit = obj.close()
+
+    def outputStream: OutputStream = this
+    override def printStream: PrintStream = new PrintStream(this)
+    override def printWriter: PrintWriter = obj match {
+      case x: PrintWriter => x
+      case _ => new PrintWriter(obj)
+    }
+  }
+
 }

scalafmt-tests/src/test/scala/org/scalafmt/cli/CliOptionsTest.scala

@@ -114,7 +114,12 @@ class CliOptionsTest extends FunSuite {
   Seq("--stdin", "--stdout").foreach { arg =>
     test(s"don't write info when using $arg") {
       val options = Cli.getConfig(Array(arg), baseCliOptionsWithOut).get
-      options.common.info match {
+      val cons = System.console()
+      if (cons ne null) options.common.info match {
+        case x: Output.FromWriter if x.obj eq cons.writer() =>
+        case x => fail(s"info should be writing to console: $x")
+      }
+      else options.common.info match {
         case x: Output.FromStream if x.obj eq Output.NoopStream.printStream =>
         case x => fail(s"info should be writing to NoopStream: $x")
       }