chore: release v5.18.0 prep

[ashutoshvarma]

Pull Request Summary
Ref #1007

Check list

• added or updated unit tests
• updated Astar official documentation
• added OnRuntimeUpgrade hook for precompile revert code registration
• updated spec version
• updated semver

[github-actions]

Package	Line Rate	Branch Rate	Health
pallets/collator-selection/src	69%	0%	➖
pallets/xc-asset-config/src	53%	0%	➖
chain-extensions/xvm/src	0%	0%	❌
chain-extensions/pallet-assets/src	0%	0%	❌
pallets/contracts-migration/src	0%	0%	❌
pallets/dapps-staking/src/pallet	85%	0%	✔
chain-extensions/types/xvm/src	0%	0%	❌
precompiles/assets-erc20/src	76%	0%	➖
precompiles/batch/src	80%	0%	✔
precompiles/sr25519/src	79%	0%	➖
precompiles/utils/macro/src	0%	0%	❌
precompiles/utils/src	68%	0%	➖
precompiles/utils/src/testing	62%	0%	➖
precompiles/xcm/src	84%	0%	✔
pallets/ethereum-checked/src	48%	0%	❌
primitives/src	64%	0%	➖
primitives/src/xcm	66%	0%	➖
pallets/block-reward/src	85%	0%	✔
pallets/custom-signatures/src	51%	0%	➖
pallets/xvm/src	46%	0%	❌
chain-extensions/dapps-staking/src	0%	0%	❌
precompiles/dapps-staking/src	93%	0%	✔
precompiles/substrate-ecdsa/src	78%	0%	➖
precompiles/xvm/src	83%	0%	✔
chain-extensions/types/dapps-staking/src	0%	0%	❌
pallets/pallet-xcm/src	53%	0%	➖
chain-extensions/types/assets/src	0%	0%	❌
pallets/dapps-staking/src	81%	0%	✔
Summary	57% (2552 / 4460)	0% (0 / 0)	➖

Minimum allowed line rate is 50%

[shaunxw]

LGTM