Add better test for localStorage

Followup from #126
I added a mock `localStorage` for environments where localStorage isn't
available, and to remove the 'store' dependency.

I've been testing more with [Bun](https://bun.com/) and I found that there,
this code doesn't reliably create the mock.

I guess in Node trying to access `window.localStorage` would throw an exception,
but that's not necessarily the case in other JS runtimes.

This commit changes it to use the `if (!('localStorage' in globalThis))` syntax,
which should work more reliably everywhere.

Author: bhousel

src/osm-auth.mjs

@@ -27,7 +27,11 @@ export function osmAuth(o) {
   // Note that accessing localStorage may throw a `SecurityError`, so wrap in a try/catch.
   var _store = null;
   try {
-    _store = window.localStorage;
+    if (!('localStorage' in globalThis)) {
+      throw new Error('No localStorage');
+    }
+    _store = globalThis.localStorage;
+
   } catch (e) {
     var _mock = new Map();
     _store = {