update precompile-xcm

[gitofdeepanshu]

Pull Request Summary

Changes

1. Add SetAppendix instruction in remote_transact() in xcm-precompile after which user can have extra fees deposited to it’s sovereign account instead of asset trap.
2. Add new function send_xcm() which allows to send any xcm-message to the destination chain.
3. Add new Struct Multilocation to precompile

struct Multilocation {
    uint8 parents;
    bytes[] interior;
}

This addition helps in getting rid of function overloading for different Account types (AccountId32 and AccountKey20) supported by xcm.

Check list

• added unit tests
• updated documentation

[Dinonard]

PR summary/message should be updated.

[Dinonard]

I'd suggest to discuss the XTokens inclusion and its impact on the interface with the team.

[Dinonard]

You shouldn't put implementation details into interface definition.

I see the old file also has this, but it's wrong.

[github-actions]

Package	Line Rate	Branch Rate	Health
chain-extensions/pallet-assets/src	0%	0%	❌
frame/custom-signatures/src	52%	0%	➖
precompiles/utils/macro/src	0%	0%	❌
precompiles/dapps-staking/src	93%	0%	✔
precompiles/utils/macro/tests	0%	0%	❌
frame/dapps-staking/src	82%	0%	✔
precompiles/xcm/src	81%	0%	✔
chain-extensions/types/dapps-staking/src	0%	0%	❌
frame/pallet-xvm/src/pallet	8%	0%	❌
frame/xc-asset-config/src	50%	0%	➖
chain-extensions/xvm/src	0%	0%	❌
frame/collator-selection/src	76%	0%	➖
frame/contracts-migration/src	0%	0%	❌
frame/pallet-xcm/src	53%	0%	➖
precompiles/assets-erc20/src	76%	0%	➖
frame/pallet-xvm/src	5%	0%	❌
precompiles/sr25519/src	79%	0%	➖
chain-extensions/types/xvm/src	0%	0%	❌
precompiles/substrate-ecdsa/src	78%	0%	➖
chain-extensions/types/assets/src	0%	0%	❌
precompiles/utils/src	66%	0%	➖
primitives/xcm/src	62%	0%	➖
frame/dapps-staking/src/pallet	87%	0%	✔
frame/block-reward/src	80%	0%	✔
precompiles/xvm/src	61%	0%	➖
chain-extensions/dapps-staking/src	0%	0%	❌
Summary	58% (3081 / 5324)	0% (0 / 0)	➖

Minimum allowed line rate is 50%