[IMPROVE] DOT max send logic

[realpaaao]

Currently the DOT max send logic is not very user friendly.

Please:

• [ ] When sending max amount deduct the correct gas to send the max amount, draining the whole address without the user manually subtracting the gas fee.

• [ ] When sending that account would fall below 1 DOT threshold, send pop up message "Keep account balance above 1 DOT. The remaining funds will be lost if balance is below 1 DOT" and prevent user to send funds.

So essentially only allow sends where remaining balance is above 1 DOT or a complete MAX send of the balance

[realpaaao]

@yvebe Please implement logic that user can't accidently lose DOT. So if user has 2 DOT and sends 1.1 or more DOT, please promt the message "Remaining balance is below 1 DOT leading to loss of funds. Please make sure you leave at least 1 DOT in the vault" . BUT allow max send to completely purge address