text: Title: Feature: AsyncAPI Kafka partitions support
  Body: Now, the following code
  
  ```python
  from faststream.specification import AsyncAPI
  from faststream.kafka import KafkaBroker, TopicPartition
  
  broker = KafkaBroker()
  
  @broker.subscriber(partitions=[TopicPartition("test", 1)])
  async def handler(): ...
  
  docs = AsyncAPI(broker)
  ```
  
  Just has no AsyncAPI representation
  
  We should provides users with a correct schema in all `subscriber` options combinations, so
  
  * [ ] Generate Channels for Kafka Subscriber in partitions case - https://github.com/airtai/faststream/blob/0.6.0/faststream/kafka/subscriber/specified.py#L20
  * [ ] Respect partition in Kafka Publisher specifciation - https://github.com/airtai/faststream/blob/0.6.0/faststream/kafka/publisher/specified.py#L31
  * [ ] Generate Channels for Confluent Subscriber in partitions case
  * [ ] Respect partition in Confluent Publisher specification 