Fix #5855: Print given for contextual function types

Author: nicolasstucki

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

@@ -183,7 +183,7 @@ class PlainPrinter(_ctx: Context) extends Printer {
         "<noprefix>"
       case tp: MethodType =>
         changePrec(GlobalPrec) {
-          (if (tp.isContextual) " with " else "") ~
+          (if (tp.isContextual) " given " else "") ~
           ("(" + (if (tp.isErasedMethod)   "erased "   else "")
                + (if (tp.isImplicitMethod && !tp.isContextual) "implicit " else "")
           ) ~ paramsText(tp) ~

compiler/test-resources/repl/i5855

@@ -0,0 +1,2 @@
+scala> def f given Int = 1
+def f given (x$1: Int): Int