withdraw widget needs "max" button

[autonome]

Is your feature request related to a problem? Please describe.

lots of crypto txn widgets have a "max" button that when clicked will autopopulate the txn amt with the maximum amount available in the target account.

please to make one for glif

Describe the solution you'd like

• a [max] button is adjacent to the amount field
• clicking the button populates the amount field w/ the total amount in the msig available to withdraw