unittest add resetOutputFormatters proc (#13267)

* add resetOutputFormatters

* remove space

* resolve comments

lib/pure/unittest.nim

@@ -96,6 +96,8 @@
 import
   macros, strutils, streams, times, sets, sequtils
 
+include "system/inclrtl"
+
 when declared(stdout):
   import os
 
@@ -186,6 +188,9 @@ proc delOutputFormatter*(formatter: OutputFormatter) =
   keepIf(formatters, proc (x: OutputFormatter): bool =
     x != formatter)
 
+proc resetOutputFormatters* {.since: (1, 1).} =
+  formatters = @[]
+    
 proc newConsoleOutputFormatter*(outputLevel: OutputLevel = OutputLevel.PRINT_ALL,
                                 colorOutput = true): <//>ConsoleOutputFormatter =
   ConsoleOutputFormatter(