Enable new solver in VSCode configuration (#157)

Not really sure we should be committing `.vscode/settings.json` to the
repo, since it blocks others from using their own config. But given that
it was added in #154, lets extend it
to force enable the new solver

Author: JohnnyMorganz

.vscode/settings.json

@@ -1,4 +1,5 @@
 {
-     "luau-lsp.sourcemap.enabled": false,
-     "luau-lsp.platform.type": "standard"
+    "luau-lsp.fflags.enableNewSolver": true,
+    "luau-lsp.sourcemap.enabled": false,
+    "luau-lsp.platform.type": "standard"
 }