Add Missing Tests for delete Account Functionality

[Agaba-derrick]

AccountClientImpl Delete Methods - Unit Tests

Overview

This set of unit tests targets the deleteAccount methods of the AccountClientImpl class, ensuring robust behavior around account deletion operations.

Key Features Tested

• Successful Account Deletion
  Validates that the ProtocolLayerClient.executeAccountDeleteTransaction method is invoked once when deleting an account.

• Account Deletion with Fund Transfer
  Tests the overloaded deleteAccount method which deletes an account and transfers remaining funds to another account, confirming correct client method invocation.

• Exception Handling
  Checks that the methods throw or propagate expected exceptions (e.g., HieroException) when invalid parameters are passed or underlying client errors occur.

Mocking Approach

• Uses Mockito to mock the ProtocolLayerClient dependency.
• Applies doNothing() for stubbing void methods properly.
• Uses assertThrows for verifying exception scenarios.
• No modifications to production code, tests rely solely on available interfaces and expected behavior.

Issue

Closes #108

[Agaba-derrick]

@Ndacyayisenga-droid @Jexsie please kindly review !

[Ndacyayisenga-droid]

Hey @Agaba-derrick. Thanks for the contribution! Could you sign the DCO https://github.com/OpenElements/hiero-enterprise-java/pull/179/checks?check_run_id=42593910068