Nim, Lua: fix sticking unary "not" operator to the number

BaseTranslator does not insert space between operator and expression.
When expression is a number, "~<number>" and "!<number>" becomes "not<number>" which is an identifier

Fixes test (1):
```
[info]   - nim:~777 *** FAILED ***
[info]     "not[]777" was not equal to "not[ ]777" (TranslatorSpec.scala:183)
[info]     Analysis:
[info]     "not[]777" -> "not[ ]777"
```

shared/src/main/scala/io/kaitai/struct/translators/LuaTranslator.scala

@@ -185,7 +185,7 @@ class LuaTranslator(provider: TypeProvider, importList: ImportList) extends Base
     case Ast.boolop.And => "and"
   }
   override def unaryOp(op: Ast.unaryop): String = op match {
-    case Ast.unaryop.Not => "not"
+    case Ast.unaryop.Not => "not "
     case _ => super.unaryOp(op)
   }
 }

shared/src/main/scala/io/kaitai/struct/translators/NimTranslator.scala

@@ -47,9 +47,9 @@ class NimTranslator(provider: TypeProvider, importList: ImportList) extends Base
   // Members declared in io.kaitai.struct.translators.CommonMethods
 
   override def unaryOp(op: Ast.unaryop): String = op match {
-    case Ast.unaryop.Invert => "not"
+    case Ast.unaryop.Invert => "not "
     case Ast.unaryop.Minus => "-"
-    case Ast.unaryop.Not => "not"
+    case Ast.unaryop.Not => "not "
   }
 
   override def booleanOp(op: Ast.boolop): String = op match {