Homa lite redeem process

Config
- type BaseWithdrawFee: Permill
- Default to expected reward for relaychain unbonding period + 1 era
- type ReserveIdentifier: ReserveIdentifier
- type RelaychainBlockNumber: BlockNumberProvider
- type ParachainAccount: Get\
Types
- type RelaychainBlockNumberOf\ = <\::RelaychainBlockNumber as BlockNumberProvider>::BlockNumber
Storages
- RedeemRequests: map AccountId => (Balance, Permill)
- (liquidAmount, additionalFee)
- AvailableStakingBalance: Balance
- ScheduledUnbonds: Vec<(Balance, RelaychainBlockNumberOf)>
- (stakingAmount, relaychain block number)
Calls
- fn request_redeem(origin, liquidAmount: Balance, additionalFee: Permill)
- if liquidAmount == 0
  - cancel redeem request
  - take RedeemRequests
  - unreserve funds if needed
  - return
- if AvailableStakingBalance > 0
  - availableLiqiuidBalance = convert AvailableStakingBalance to liquid balance with exchange rate
  - redeem up to availableLiqiuidBalance
  - if no more liquidAmount, return
  - no need to pay fee for redeem tokens in AvailableStakingBalance
- reserve / unreserve liquidAmount
- override RedeemRequests
- fn mint(origin, stakingAmount: Balance, xcm_dest_weight: Weight)
- iterate RedeemRequests
  - match request, transfer staking token to requester, and repatriate reserved liquid token to minter
  - adjust the exchange rate with BaseWithFee + additional fee so redeem requester paying the fee to minter
- if more stakingAmount left, go with original mint process
- fn mint_for_requests(origin, stakingAmount: Balance, xcm_dest_weight: Weight, requests: Vec\)
- iterate requests
  - match request, transfer staking token to requester, and repatriate reserved liquid token to minter
  - adjust the exchange rate with BaseWithFee + additional fee so redeem requester paying the fee to minter
  - remove completed requests, update incompleted requests
- if more stakingAmount left, call mint
- fn schedule_unbond(origin, stakingAmount: Balance, unbond_block: RelaychainBlockNumberOf)
- ensure GovernanceOrigin
- update ScheduledUnbonds
- fn replace_scheduled_unbonds(origin, Vec<(Balance, RelaychainBlockNumberOf)>)
- ensure GovernanceOrigin
- update ScheduledUnbonds
- this should only be used to correct mistaken call of schedule_unbond or if something unexpected happened on relaychain
Hooks
- on_idle(n: BlockNumber, remaining_weight: Weight)
- required_weight = WeightInfo::on_idle()
- if remaining_weight > required_weight
  - take first item of ScheduledUnbonds
  - if past relaychain block number
  - make XCM call to utility.batchAll([staking.withdrawUnbonded(), balances.transfer(parachain_account, stakingAmount)])
  - update ScheduledUnbonds
  - match redeem request
  - update AvailableStakingBalance
  - return required_weight
- return 0

AcalaNetwork / Acala

Homa lite redeem process #1313