Alerting: Add optional metadata via query param to silence GET requests

[JacobsonMT]

What is this feature?

Adds a query param options ruleMetadata=true and accesscontrol=true to /alertmanager/grafana/api/v2/silences and alertmanager/grafana/api/v2/silence/{SilenceId}

ruleMetadata=true will add a new metadata field containing rule_uid, rule_title, folder_uid for rule-specific silences.
accessconntrol=true will add a top-level accessControl field containing user permissions on each silence (read/write/create)

Ex:

{
  "accessControl": {
    "create": false,
    "read": true,
    "write": false
  },
  "comment": "test comment",
  "createdBy": "someone",
  "endsAt": "2026-04-18T18:07:26.993Z",
  "id": "e95bcdc3-97a2-44c1-9361-5ec1d12f9f9e",
  "matchers": [{"isEqual": true,"isRegex": false,"name": "__alert_rule_uid__","value": "load_folder0_group3_alert1"}],
  "metadata": {
    "rule_uid": "load_folder0_group3_alert1",
    "rule_title": "group3_alert1",
    "folder_uid": "edmpbowggnm68d"
  },
  "startsAt": "2024-05-24T20:06:18.670Z",
  "status": {
    "state": "active"
  },
  "updatedAt": "2024-05-24T20:06:18.670Z"
}

Why do we need this feature?

This is needed to:

• Allow the UI to display useful rule information for rule-specific silences without heavy cross-reference API calls.
• Allow the UI to simplify logic on access control for deciding when to display permission-specific components.

[yuri-tceretian]

I tested it and it works as expected. Just few comments\suggestions in comments and

1. I am not sure create field makes sense in per-silence access control field. WDYT?
2. It would be great to update our integration tests. Separate PR is fine, though.

[yuri-tceretian]

LGTM! Really like the direction we're taking!

[tomratcliffe]

I checked with my changes from the UI portion and it looks to be working great on my setup 💯 query params/property names are all aligned now, thanks!