Improve `APIError` default exception messages

[pederhan]

When an uncaught exception is raised because of an HTTP status error, no useful information is printed by default.

Take this example of a traceback (rich-formatted in this case):

│ /Users/pederhan/repos/mreg-tools/.venv/lib/python3.14/site-packages/mreg_api/client.py:610 in _check_response                                            │
│                                                                                                                                                          │
│    607 │   │   │   else:                                                                                                                                 │
│    608 │   │   │   │   msg = response.text                                                                                                               │
│    609 │   │   │   cls = determine_http_error_class(operation_type)                                                                                      │
│ ❱  610 │   │   │   raise cls(msg, response)                                                                                                              │
│    611 │                                                                                                                                                 │
│    612 │   def request(                                                                                                                                  │
│    613 │   │   self,                                                                                                                                     │
╰──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╯
GetError: 500 Internal Server Error

I suppose we should try to include response text?