DX: Transaction class refactor

[Abdeali099]

1. use new_doc

transaction-parser/transaction_parser/transaction_parser/controllers/transaction.py

Line 39 in adcb5ef

self.doc = frappe.get_doc({"doctype": self.DOCTYPE})

2. No need to pass ai_model

transaction-parser/transaction_parser/transaction_parser/controllers/transaction.py

Line 73 in adcb5ef

self, ai_model: str | None = None, page_limit: int | None = None

3. Can use @abstractmethod

transaction-parser/transaction_parser/transaction_parser/controllers/transaction.py

Line 258 in adcb5ef

raise NotImplementedError(