fluentbit(kafka): Add support for format:raw and raw_log_key

[laokoukou]

Describe the issue

I want to send raw content to kafka. Offical's fluent-bit can setting the field [format: raw] and [raw_log_key: log].
doc: https://docs.fluentbit.io/manual/data-pipeline/outputs/kafka#fluent-bit.yaml-2

But fluent-operator's kafka configuration is missing：
1）the field [format] is missing the optional: raw
2）missing the field [raw_log_key]

To Reproduce

[2026/02/25 12:54:40.569171481] [error] [output:kafka:kafka.0] missing raw_log_key
[0] data.special_server.tlog_9999_prod.app.app-68fff894d8-d7tnw.app_tlog56_20260225_20.log: [[1772024140.423744930, {}], {"log"=>"111111111111111111111111"}]

Expected behavior

support the field [raw_log_key] and [format: raw] to fix the error

Your Environment

- Fluent Operator version:3.6.0
- Container Runtime: v1.6.39
- Operating system:alinux 3.2
- Kernel version:5+

How did you install fluent operator?

No response

Additional context

kubectl apply -f setup.yaml

[joshuabaird]

@laokoukou Hi! Would you be willing to submit a PR for this enhancement?