List custom rules

Example response

{
  "custom_rules": [
    {
      "id": 1,
      "semgrep_rule": "rules:\n- id: CUSTOM-RULE-1\n  pattern: console.log(...)\n  message: Semgrep found a debug statement\n  languages: [javascript]\n  severity: WARNING",
      "issue_title": "console.log",
      "priority": 20,
      "tldr": "console.log should be avoided in frontend applications",
      "how_to_fix": "remove the console.log",
      "language": "JS",
      "has_error": false
    }
  ]
}