## Description 

Please refer to this SIP draft: 
https://github.com/sui-foundation/sips/pull/19

The PR focuses only on consensus related changes, covering both Narwhal
and Mysticeti.
We will proceed to work on the remaining parts once this gets merged.

The PR includes a commit from @mwtian that changes `TransactionConsumer`
for ack handling in a bundle context.
Special thanks to @mwtian for taking time to discussions and authoring
the change above!


## Test Plan 

The feature is not exactly user-facing and do not break anything.

### Type of Change (Check all that apply)

- [x] protocol change
- [ ] user-visible impact
- [ ] breaking change for a client SDKs
- [ ] breaking change for FNs (FN binary must upgrade)
- [ ] breaking change for validators or node operators (must upgrade
binaries)
- [ ] breaking change for on-chain data layout
- [ ] necessitate either a data wipe or data migration

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Co-authored-by: Mingwei Tian <mingwei@mystenlabs.com>