[xcm_builder]: Do not consume `msg` on `NotApplicable` for remote exporters (#1519)

## Summary

Implementations of `SendXcm`'s `validate` should not consume `dest`
and/or `msg` parameters in case of `NotApplicable` error.
This commit aligns expected behavior for `UnpaidRemoteExporter` and
`SovereignPaidRemoteExporter`.

## Testing

Added `remote_exporters_does_not_consume_dest_or_msg_on_not_applicable`
test which checks two possible cases:
- `dest` is local
- no configured exporter for `dest`