Add workaround to reserve transfer native assets

[0x7CFE]

Currently we identify assets being transferred by specifying an H160 style address (XC20), so this prevents us from sending native token since there's no representation for it.

This PR adds a workaround to interpret address 0x0 as native token to be sent (parents: 0, interior: Here), it can be used to pay for transaction.

[Dinonard]

At this point, it might be worth doing the UT improvement item for XCM precompiles.

It would be good to check that in case msg.value > 0 we get a modified asset list in the dispatched XCM.

[0x7CFE]

It would be good to check that in case msg.value > 0 we get a modified asset list in the dispatched XCM.

Agree. Current solution looks ad-hoc and fragile.

[0x7CFE]

Documented recent changes in API in https://github.com/AstarNetwork/astar-docs/pull/130

[github-actions[bot]]

Package	Line Rate	Branch Rate	Health
chain-extensions/dapps-staking/src	0%	0%	❌
chain-extensions/types/rmrk/src	0%	0%	❌
chain-extensions/xvm/src	0%	0%	❌
precompiles/dapps-staking/src	93%	0%	✔
precompiles/utils/src/data	72%	0%	➖
chain-extensions/types/xvm/src	0%	0%	❌
frame/pallet-xcm/src	65%	0%	➖
frame/custom-signatures/src	57%	0%	➖
frame/pallet-xvm/src	11%	0%	❌
precompiles/sr25519/src	79%	0%	➖
frame/dapps-staking/src/pallet	90%	0%	✔
frame/block-reward/src	85%	0%	✔
frame/xc-asset-config/src	70%	0%	➖
frame/dapps-staking/src	83%	0%	✔
frame/collator-selection/src	80%	0%	✔
frame/pallet-xvm/src/pallet	34%	0%	❌
chain-extensions/rmrk/src	0%	0%	❌
precompiles/assets-erc20/src	73%	0%	➖
precompiles/substrate-ecdsa/src	78%	0%	➖
precompiles/utils/macro/src	0%	0%	❌
precompiles/utils/macro/tests	0%	0%	❌
precompiles/xcm/src	84%	0%	✔
precompiles/xvm/src	94%	0%	✔
primitives/xcm/src	68%	0%	➖
precompiles/utils/src	72%	0%	➖
chain-extensions/types/dapps-staking/src	0%	0%	❌
Summary	60% (2581 / 4332)	0% (0 / 0)	➖

Minimum allowed line rate is 50%