Refactor low-level transactions to `DatabaseTransaction/Repository->t…

…ransaction()` API to handle nested transactions

- Important: It is recommended to update transactions to use new `DatabaseTransaction` API to ensure correct transaction handling within nested transactions.
- Introduced new `DatabaseTransaction` API usable directly via DI or via `Repository->getTransaction()`

remp/crm#3330

src/Repositories/InvoicesRepository.php

@@ -123,7 +123,7 @@ final public function updateItems(ActiveRow $invoice): void
     {
         $payment = $invoice->related('payments')->fetch();
 
-        $this->getDatabase()->transaction(function () use ($invoice, $payment) {
+        $this->getTransaction()->wrap(function () use ($invoice, $payment) {
             $this->invoiceItemsRepository->getTable()->where([
                 'invoice_id' => $invoice->id,
             ])->delete();