Add transfer events to `CurrencyAdapter`?

[apopiak]

Functions implemented for Currency do not emit events currently. E.g. deposit_creating here

This makes it difficult to trace transfers when these functions are called e.g. via XCM. (As surfaced by #3489)

Should we address this in the underlying implementation or do we expect the callers to generate the events?
We could adjust the CurrencyAdapter to add events. (Similar question arises for the FungiblesAdapter, of course, though the fungibles implementation in the assets pallet does emit events for mint, burn and transfer.)

[gavofyork]

Should happen either as part of the CurrencyAdapter implementation or, better I think, inside XcmExecutor, as a sort of "trace". Low-level utilities (such as deposit_creating) should not be emitting events.

[apopiak]

adressed by paritytech/substrate#9425