Custom formatter for SemanticLogger elasticsearch appender

[dmitry-sinina]

Idea is to use custom formatter to extract tags from named_tags hash to top level json attibutes.

current format:

    "_time": "2025-06-26T11:53:24.207443435Z",
    "_stream_id": "0000000000000000abaa950ac3f8300ff10e29a3b27a0c74",
....
    "name": "ActiveAdmin::Devise::SessionsController",
    "named_tags.env": "staging",
    "named_tags.system": "yeti",
    "named_tags.request_id": "a744b32f-4428-41bc-bc07-660b2c4910c1",
    "payload.action": "new",
...
  }

new format:

    "_time": "2025-06-26T11:53:24.207443435Z",
    "_stream_id": "0000000000000000abaa950ac3f8300ff10e29a3b27a0c74",
....
    "name": "ActiveAdmin::Devise::SessionsController",
    "env": "staging",
    "system": "yeti",
    "request_id": "a744b32f-4428-41bc-bc07-660b2c4910c1",
    "payload.action": "new",
...
  }

Currently elasticsearch appender using default formatter - raw_json

• Create custom formatter https://logger.rocketjob.io/customize.html New formatter should work in same was as raw_json but extract keys from named_tags to object top level
• Use new formatter in config/initializers/semantic_logger.rb SemanticLogger.add_appender