Basic static price provider pallet

[Dinonard]

Pull Request Summary

Introduces a basic pallet to handle active native currency price setting.
This is used when calculating dApp tier slots & rewards.

The proper solution will be done in the future via oracle, but for now, a privileged
call for price setting is enabled.

[ashutoshvarma]

LGTM

[shaunxw]

Will be helpful to have a docstring of pallet descriptions.

[Dinonard]

Sure, will do it before the merge.

[PierreOssun]

LGTM

[github-actions]

Package	Line Rate	Branch Rate	Health
pallets/xvm/src	40%	0%	❌
pallets/block-rewards-hybrid/src	87%	0%	✔
pallets/dapps-staking/src	81%	0%	✔
pallets/dapp-staking-v3/src/benchmarking	0%	0%	❌
pallets/dapp-staking-migration/src	39%	0%	❌
pallets/inflation/src	70%	0%	➖
pallets/ethereum-checked/src	48%	0%	❌
precompiles/xvm/src	74%	0%	➖
precompiles/assets-erc20/src	81%	0%	✔
primitives/src/xcm	66%	0%	➖
pallets/dapp-staking-v3/src	76%	0%	➖
pallets/dapps-staking/src/pallet	85%	0%	✔
pallets/dapp-staking-v3/rpc/runtime-api/src	0%	0%	❌
chain-extensions/types/unified-accounts/src	0%	0%	❌
precompiles/substrate-ecdsa/src	74%	0%	➖
precompiles/unified-accounts/src	100%	0%	✔
pallets/xc-asset-config/src	53%	0%	➖
pallets/dynamic-evm-base-fee/src	81%	0%	✔
chain-extensions/types/xvm/src	0%	0%	❌
chain-extensions/xvm/src	0%	0%	❌
pallets/static-price-provider/src	61%	0%	➖
pallets/unified-accounts/src	84%	0%	✔
precompiles/dapp-staking-v3/src	90%	0%	✔
precompiles/sr25519/src	64%	0%	➖
chain-extensions/pallet-assets/src	0%	0%	❌
chain-extensions/unified-accounts/src	0%	0%	❌
precompiles/dapp-staking-v3/src/test	0%	0%	❌
precompiles/xcm/src	72%	0%	➖
pallets/dapp-staking-v3/src/test	0%	0%	❌
chain-extensions/types/assets/src	0%	0%	❌
primitives/src	66%	0%	➖
pallets/collator-selection/src	69%	0%	➖
precompiles/dapps-staking/src	94%	0%	✔
Summary	67% (3182 / 4733)	0% (0 / 0)	➖

Minimum allowed line rate is 50%