FINERACT-2752: Charge - Income from charge list is not the same on add and edit mode

[rymghosn]

When creating a charge with chargeAppliesTo = Client and selecting an item from the "Income from Charge" (GL income account) list, editing that
charge afterwards showed the previously selected income account as missing, and reopening the dropdown showed fewer available options than
before.

Root cause: ChargeWritePlatformServiceJpaRepositoryImpl#updateCharge persisted the updated charge with a plain chargeRepository.save(). This
defers the actual flush to Hibernate's own timing, so when the same request cycle immediately re-read the charge to build the response (or to
populate the edit-mode dropdown), it could still see the pre-update state — making the income account selection look reverted or absent.

Fix:

• updateCharge now calls chargeRepository.saveAndFlush() instead of save(), so the change is flushed before the charge is re-read.
• Added the missing incomeAccountId field to ChargeRequest so the API request DTO accurately reflects the incomeAccountId parameter the service
  already accepts (ChargesApiConstants.glAccountIdParamName).
  PR:(https://issues.apache.org/jira/browse/FINERACT-2752)