fix: add lfs to luarc.json (#20979)

The sumneko lua language server keeps prompting me if I want to
"configure my workspace for lfs". These changes suppress that prompt.

contrib/luarc.json

@@ -10,13 +10,16 @@
           "before_each",
           "after_each",
           "setup",
-          "teardown"
+          "teardown",
+          "lfs"
         ]
     },
     "workspace": {
-        "library": {
-            "runtime/lua": true
-        },
+        "library": [
+            "runtime/lua",
+            "${3rd}/lfs/library"
+        ],
+        "checkThirdParty": false,
         "maxPreload": 2000,
         "preloadFileSize": 1000
     },