Improvements for kip-360 support / #5362

[VadimPlh]

Have to improve:

• Delete dispatching for init_tm_tx request. Kafka does not do it
• Use serde for tm_transaction structure
• Fix enum tx_status. Add type for it (Need to check it)
• Fix upgrade test consume phase

This is a follow-up to PR https://github.com/redpanda-data/redpanda/pull/5362