XCM native fee reduction

[Dinonard]

Pull Request Summary

Solution suggestion to reduce XCM fees when paid in native.

Overview
With the introduction of fee alignment, native fees have been slightly increased according to the
proposed Tokenomics 2.0 model (here).

A thing that was missed is the impact of this on XCM fees.
The way XCM fees are calculated, in general, is static. We, as the Substrate/Polkadot ecosystem, don't yet have a good mechanism for the fetching of dynamic prices.

To minimize the impact, this PR suggests to reuse the existing WeightToFee struct which as the name says, converts Weight component into numeric fee (e.g. how much ASTR needs to be paid), but multiplies that fee with the minimum possible allowed value of the adjustment factor (the adjustment factor is used when calculating fees for the native transactions).

Fee Overview

At the moment, all our runtimes have hardcoded XCM instruction ref time weight to 1_000_000_000 (picoseconds).
Base fee per gas is set to 98_974_000 for all runtimes as well.
Using that information we can express price per instruction:

---	Astar	Shiden	Shibuya
Price Per Base Weight	0.0030855	0.000030855	0.0030855
Price Per Instruction	0.03177	0.0003177	0.03177

Taking into account an average sequence with fixed weights, the price for execution on Astar will be around 0.2 ASTR per sequence.

NOTE: This was calculated outside of runtime scope so real numbers might differ on-chain.

[shaunxw]

The direction looks good to me. IMO we need checks on local fork to see how much XCM fees needed for common cross-chain transfers with this solution.

[PierreOssun]

LGTM

[github-actions]

Package	Line Rate	Branch Rate	Health
precompiles/utils/src	55%	0%	➖
chain-extensions/types/xvm/src	0%	0%	❌
pallets/xvm/src	40%	0%	❌
chain-extensions/pallet-assets/src	0%	0%	❌
chain-extensions/types/dapps-staking/src	0%	0%	❌
pallets/dapps-staking/src	81%	0%	✔
precompiles/assets-erc20/src	77%	0%	➖
chain-extensions/dapps-staking/src	0%	0%	❌
primitives/src/xcm	66%	0%	➖
precompiles/xcm/src	75%	0%	➖
pallets/collator-selection/src	69%	0%	➖
chain-extensions/types/unified-accounts/src	0%	0%	❌
pallets/block-rewards-hybrid/src	87%	0%	✔
pallets/dapps-staking/src/pallet	85%	0%	✔
precompiles/dapps-staking/src	93%	0%	✔
pallets/xc-asset-config/src	53%	0%	➖
precompiles/utils/macro/src	0%	0%	❌
pallets/block-reward/src	85%	0%	✔
chain-extensions/xvm/src	0%	0%	❌
chain-extensions/unified-accounts/src	0%	0%	❌
precompiles/utils/src/testing	38%	0%	❌
precompiles/xvm/src	75%	0%	➖
pallets/contracts-migration/src	0%	0%	❌
pallets/ethereum-checked/src	48%	0%	❌
precompiles/substrate-ecdsa/src	78%	0%	➖
precompiles/sr25519/src	79%	0%	➖
chain-extensions/types/assets/src	0%	0%	❌
pallets/unified-accounts/src	83%	0%	✔
pallets/dynamic-evm-base-fee/src	81%	0%	✔
primitives/src	65%	0%	➖
Summary	57% (2275 / 4014)	0% (0 / 0)	➖

Minimum allowed line rate is 50%

[PierreOssun]

LGTM