Add Login Status API

Close #1608, adding the suggested spec to the list.

### Changes to `index.json`
This update would trigger the following changes in `index.json`:

<details><summary>Add spec (1)</summary>

```json
{
  "url": "https://w3c-fedid.github.io/login-status/",
  "seriesComposition": "full",
  "shortname": "login-status",
  "series": {
    "shortname": "login-status",
    "currentSpecification": "login-status",
    "title": "Login Status API",
    "shortTitle": "Login Status API",
    "nightlyUrl": "https://w3c-fedid.github.io/login-status/"
  },
  "organization": "W3C",
  "groups": [
    {
      "name": "Federated Identity Working Group",
      "url": "https://www.w3.org/groups/wg/fedid/"
    }
  ],
  "nightly": {
    "url": "https://w3c-fedid.github.io/login-status/",
    "status": "Editor's Draft",
    "alternateUrls": [],
    "repository": "https://github.com/w3c-fedid/login-status",
    "sourcePath": "spec/index.bs",
    "filename": "index.html"
  },
  "title": "Login Status API",
  "source": "spec",
  "shortTitle": "Login Status API",
  "categories": [
    "browser"
  ],
  "standing": "good"
}
```
</details>

### Tests
These changes look good! 😎

specs.json

@@ -504,6 +504,7 @@
   "https://testutils.spec.whatwg.org/",
   "https://url.spec.whatwg.org/",
   "https://urlpattern.spec.whatwg.org/",
+  "https://w3c-fedid.github.io/login-status/",
   "https://w3c.github.io/at-driver/",
   "https://w3c.github.io/contentEditable/",
   {

src/data/monitor.json

@@ -413,10 +413,6 @@
     "https://wicg.github.io/document-isolation-policy/": {
       "comment": "Chrome status entry https://chromestatus.com/feature/5141940204208128 says no active development and no known standard positions yet",
       "lastreviewed": "2024-11-01"
-    },
-    "https://w3c-fedid.github.io/login-status/": {
-      "comment": "FedCM still contains the Login Status API as sub-section for now (and TR link actually targets it, which will likely confuse tooling)",
-      "lastreviewed": "2024-11-01"
     }
   }
 }