Companion for polkadot#7234 (XCM: Tools for uniquely referencing messages)

[gavofyork]

Companion to fix for new API. Also moves DenyThenTry and DenyReserveTransferToRelayChain into Polkadot.

This revamps some of the *MPQ events to correctly report both the message hash and ID. It also moves the *MPQ code over to use ExecuteXcm::prepare_and_execute rather than the older APIs, which required simplifying some tests since the new API is at a slightly lower level.

• Changes of message hash/ID should be respected in any events deposited
  • DMP arrival/dispatch (Cumulus)
  • XCMP arrival/dispatch (Cumulus)
  • Consider adding the ID into existing send events
• Integrate into parachains (Cumulus)

[bkontur]

@gavofyork
there is one older TODO here

    // We aren't able to track the XCM that initiated the fee deposit, so we create a
    // fake message hash here
    &XcmContext::with_message_hash([0; 32]),

could this be fixed now with this new message_id/topic stuff?
my guess is maybe to change trait for trader here (extends with context: &XcmContext),

wdyt?

[gavofyork]

could this be fixed now with this new message_id/topic stuff?

These changes don't much help this.

In fact, the functions inside WeightTrader and TakeRevenue and perhaps some other hook-traits used by XcmExecutor should all take XcmContext. This is quite a substantial change in APIs so should get its own issue and PR. Feel free to create the issue.

[ordian]

approval stamp to unblock the companion check