Create storage API for removing Encumbrance transactions

Purpose/Overview:
We should support deleting only Encumbrance transactions, which are not connected to invoice and have not yet paid

Requirements:
API for removing Encumbrance transaction should be checked and updated if needed

Approach:
Only allow deleting encumbrance transactions which are not connected to an invoice and have not been paid yet.

!Note : Despite the fact that this is storage module, we need to add business logic here to prevent the occurrence of inconsistency in the results of financial operations and amounts

Acceptance criteria:
API updated with related unit tests