Moved json enum index test to the proper file (#16826)

tests/stdlib/tjson_enum_index.nim

@@ -1,11 +0,0 @@
-import json
-type Test = enum
-  one, two, three, four, five
-let a = [
-  one: 300,
-  two: 20,
-  three: 10,
-  four: 0,
-  five: -10
-]
-doAssert (%* a).to(a.typeof) == a

tests/stdlib/tjsonmacro.nim

@@ -633,6 +633,18 @@ proc testJson() =
     except KeyError:
       doAssert getCurrentExceptionMsg().contains ".member.list[2].value"
 
+  block:
+    # Enum indexed array test
+    type Test = enum
+      one, two, three, four, five
+    let a = [
+      one: 300,
+      two: 20,
+      three: 10,
+      four: 0,
+      five: -10
+    ]
+    doAssert (%* a).to(a.typeof) == a
 
 
 testJson()