build.fsx,fsharplint.json: enable TypePrefixing rule for SelfCheck

With Mode=Always.

Author: webwarrior-ws

build.fsx

@@ -274,7 +274,6 @@ Target.create "SelfCheck" (fun _ ->
             "trailingWhitespaceOnLine"
 
             // TODO: we should enable at some point
-            "typePrefixing"
             "unnestedFunctionNames"
             "nestedFunctionNames"
             "nestedStatements"

fsharplint.json

@@ -0,0 +1,8 @@
+{
+    "typePrefixing": {
+        "enabled": true,
+        "config": {
+            "mode": "Always"
+        }
+    }
+}