Auto-revoke token approvals on submit page

[jfschwarz]

When submitting a batch that includes any ERC20 token approvals we should allow the user to revoke all given approvals at the end of the batch.

It should actually be the default behavior: A checkbox revoke all token approvals should be pre-selected by default. Next to the checkbox label we should display an info bubble (i) that on hover shows the following explanation:

The transaction bundle you are about to submit includes token approvals, which grant certain dApps permission to spend your tokens. If you don’t revoke these approvals, the dApps will retain the ability to spend your tokens indefinitely. Maintain full control by atomically revoking any leftover approval balances as a final step in the transaction.

The checkbox should not be displayed if there are no approvals in the batch.

Approvals should be detected based on transaction event logs (Approval(address owner, address spender, uint256 value) event).

If the checkbock is selected, upon submit it should add the required extra calls to the bundle to be passed for signing. These calls should not appear in the right panel for now.

[auryn-macmillan]

This is a really nice feature idea!