Allow specifying native gas token amount

[r0wdy1]

• Add nativeAmount argument to withdrawMulti. That will allow user to automatically swap specified amount of funds to the native gas token of the current network for further transactions.
  • The amount must be specified in standard minimal units of account for the current Pool token .
  • Check that specified amount is less than withdrawal amount minus relayer fee
• relayer: corresponding extra field on transactions API, pass the field to contract

Additional info

• Design draft https://www.figma.com/file/VgEAclPmc6tghBwaSfTWAn/zkBob-App?type=design&node-id=4695-97279&t=kbxnn26N0mCGEoXW-0

• The contract https://github.com/zkBob/zkbob-contracts/blob/master/src/utils/UniswapV3Seller.sol

• UI task: Auto convert some amount of tokens to native token zkbob-ui#189

• Relayer task: Native amount handling zeropool-relayer#174

[EvgenKor]

Which logic should be applied inside transaction memo block? I have no questions on native_amount field in the memo block. But should we decrease delta_token value in that case?

[r0wdy1]

may be we shouldn't change the memo? this has nothing to do with the protocol. AFAIK there are no plans to change history view. From the protocol standpoint it's the same ol' withdrawal but with extra automation