Allow Proposal Delete from Delegate that created it

[DefiDebauchery]

In the API docs for v1_multisig-transactions_delete

Only the proposer can delete the transaction.
If the transaction was proposed by a delegate, the Safe owner who delegated to the delegate must be used.

Since we have the proposer via #1592, the Delegate that proposed a transaction should be permitted to delete it. This would allow for automated management -- we have Discord-based management of some tasks, and being able to undo a mistake without an explicit reject transaction (and without using the parent key!) would be helpful.

[Uxio0]

Your proposal makes a lot of sense, we will implement it

[JagoFigueroa]

Tested and verified 😄