[Validator Staking] Update withdraw_funds to withdraw contract's balance

[cowboy0015]

Description

Funds can be locked at the contract due to various reasons.

Possible cases are

• bin2chen - when a validator is kicked out of the bonded validator set ,unstake funds will remain in the contract sherlock-audit/2024-05-andromeda-ado-judging#41
• bin2chen - execute_stake() without setting DistributionMsg::SetWithdrawAddress, partial reward may remain in the contract sherlock-audit/2024-05-andromeda-ado-judging#42
• bin2chen - If WithdrawAddrEnabled = false, execute_claim() will fail sherlock-audit/2024-05-andromeda-ado-judging#43
• bin2chen - if Slash Validator occurs, UNSTAKING_QUEUE's unstake amount will not be accurate sherlock-audit/2024-05-andromeda-ado-judging#44
• J4X_ - Attacker can freeze users first rewards sherlock-audit/2024-05-andromeda-ado-judging#50
• J4X_ - Staked tokens can never be retrieved due to old cosmos-sdk version on targeted chains sherlock-audit/2024-05-andromeda-ado-judging#53

As it can be seen from above audit results, funds can be locked in the contract due slashed or kicked validators, validator versions and validator config. To deal with frozen funds in any unexpected situation, we need to update the withdraw_funds to withdraw the whole contract balance.

Implementation

Add following parameters to the execute_withdraw_fund function.

• denom: Option
• recipient: Option

If denom is None, contract's all balance will be gained using AllBalanceResponse and withdraw all balances.

If recipient is None, info.sender will be used as the withdraw address

Acceptance Criteria

• withdraw_funds that returns the contract's balance
• unit tests
• integration test