Added `ExecuteWithOrigin` instruction according to the old XCM RFC 38:
https://github.com/polkadot-fellows/xcm-format/pull/38.

This instruction allows you to descend or clear while going back again.

## TODO
- [x] Implementation
- [x] Unit tests
- [x] Integration tests
- [x] Benchmarks
- [x] PRDoc

## Future work

Modify `WithComputedOrigin` barrier to allow, for example, fees to be
paid with a descendant origin using this instruction.

---------

Signed-off-by: Adrian Catangiu <adrian@parity.io>
Co-authored-by: Adrian Catangiu <adrian@parity.io>
Co-authored-by: Andrii <ndk@parity.io>
Co-authored-by: Branislav Kontur <bkontur@gmail.com>
Co-authored-by: Joseph Zhao <65984904+programskillforverification@users.noreply.github.com>
Co-authored-by: Nazar Mokrynskyi <nazar@mokrynskyi.com>
Co-authored-by: Bastian Köcher <git@kchr.de>
Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>
Co-authored-by: command-bot <>