(core) Simple localization support and currency selector.

Summary:
- Grist document has a associated "locale" setting that affects how currency is formatted.
- Currency selector for number format.

Test Plan: not done

Reviewers: dsagal

Reviewed By: dsagal

Subscribers: paulfitz

Differential Revision: https://phab.getgrist.com/D2977

app/server/tsconfig.json

@@ -1,7 +1,7 @@
 {
   "extends": "../../buildtools/tsconfig-base.json",
   "references": [
-    { "path": "../common" }
+    { "path": "../common" },
   ],
   "include": [
     "**/*",