Allow passing custom plpgsql_check arguments via config

It would be helpful if the Postgres Language Server allowed users to pass named arguments directly to plpgsql_check_function() / plpgsql_check_function_tb() through postgres-language-server.jsonc.

A generic config like this would provide much more flexibility:

{
  "plpgsqlCheck": {
    "enabled": true,
    "functionArgs": {
      "other_warnings": false,
      "fatal_errors": false,
      "performance_warnings": false
    }
  }
}

It would also be useful to support an exclude pattern for diagnostics, so specific known messages can be hidden without disabling an entire warning category. For example:

{
  "plpgsqlCheck": {
    "enabled": true,
    "functionArgs": {
      "other_warnings": true
    },
    "excludeMessages": [
      "too many attributes for target variables"
    ]
  }
}

That would make it easier to reduce noisy diagnostics while still keeping plpgsql_check enabled.