[misc] prepare for monorepo

- add git ignore entries
- create package-lock.json

libraries/settings/.gitignore

@@ -0,0 +1,2 @@
+.npmrc
+Dockerfile

libraries/settings/package-lock.json

@@ -0,0 +1,5 @@
+{
+  "name": "@overleaf/settings",
+  "version": "2.1.1",
+  "lockfileVersion": 1
+}