Closes: #4003 (please
see for the problem description)

## TODO
- [x] add more tests covering `WrapVersion` corner cases (e.g. para has
lower version, ...)
- [x] regenerate benchmarks `runtime_parachains::hrmp` (fix for Rococo
is here: #4332)

## Questions / possible improvements
- [ ] A `WrapVersion` implementation for `pallet_xcm` initiates version
discovery with
[note_unknown_version](https://github.com/paritytech/polkadot-sdk/blob/master/polkadot/xcm/pallet-xcm/src/lib.rs#L2527C5-L2527C25),
there is possibility to avoid this overhead in this HRMP case to create
new `WrapVersion` adapter for `pallet_xcm` which would not use
`note_unknown_version`. Is it worth to do it or not?
- [ ] There's a possibility to decouple XCM functionality from the HRMP
pallet, allowing any relay chain to generate its own notifications. This
approach wouldn't restrict notifications solely to the XCM. However,
it's uncertain whether it's worthwhile or desirable to do so? It means
making HRMP pallet more generic. E.g. hiding HRMP notifications behind
some trait:
	```
	trait HrmpNotifications {

		fn on_channel_open_request(
			sender: ParaId,
			proposed_max_capacity: u32,
			proposed_max_message_size: u32) -> primitives::DownwardMessage;

fn on_channel_accepted(recipient: ParaId) ->
primitives::DownwardMessage;

fn on_channel_closing(initiator: ParaId, sender: ParaId, recipient:
ParaId) -> primitives::DownwardMessage;
	}
	```
and then we could have whatever adapter, `impl HrmpNotifications for
VersionedXcmHrmpNotifications {...}`,
	```
	impl parachains_hrmp::Config for Runtime {
	..
		type HrmpNotifications = VersionedXcmHrmpNotifications;
	..
	}
	```

---------

Co-authored-by: command-bot <>
Co-authored-by: Bastian Köcher <git@kchr.de>