Single transaction approval

[sadhbh-c0d3]

• Use single off-chain permit signed only once by wallet, rest done by service
• Modify OTCIndex.deposit() smart-contract method
• Modify OTCCustody.addresToCustody() smart-contract method
• Remove multi-step dialog from FE
• Clicking "Confirm" should prompt wallet to sign transaction
• Send order immediatelly after transaction is signed
• When service recieves NewIndexOrder, it will call OTCIndex.deposit()

We don't need to do three steps: send order, approve, execute deposit. Instead all we need is approve and send order automatically after approve. System can take over and call deposit.