Fix printing of classes with companion objects in the decompiler (#4526)

This fixes printing of classes with companion objects so that they don't appear on the same line.
Example case:

class Foo
object Foo

will be decompiled into

class Foo() {}
object Foo {}

where before they would be printed on the same line, failing compilation.

Author: fschueler

compiler/src/dotty/tools/dotc/printing/DecompilerPrinter.scala

@@ -38,7 +38,7 @@ class DecompilerPrinter(_ctx: Context) extends RefinedPrinter(_ctx) {
     }
     val statsText = stats match {
       case (pdef: PackageDef) :: Nil => toText(pdef)
-      case _ => toTextGlobal(stats, "\n")
+      case _ => Fluid(toTextGlobal(stats, "\n") :: Nil)
     }
     val bodyText =
       if (tree.pid.symbol.isEmptyPackage) statsText

tests/pos/classWithCompObj.decompiled

@@ -0,0 +1,3 @@
+/** Decompiled from out/posTestFromTasty/pos/classWithCompObj/Foo.class */
+class Foo() {}
+object Foo {}

tests/pos/classWithCompObj.scala

@@ -0,0 +1,2 @@
+class Foo
+object Foo