LCFS - BUG - Transaction Effective date

**Describe the Bug**
The Effective date on the new Transaction page should default to null, yyyy-mm-dd, and allow a transaction to be saved with a null value.

Presently it defaults to todays date and cannot be saved with a null value.

**Implications**
The majority of transactions will not have an effective date, having to clear this fields makes for very probable errors in this date.

**Steps To Reproduce**
Steps to reproduce the behaviour:
User/Role: idir\analyst
1. Go to Transactions / New transaction


Start at Transactions / New transaction and reproduce the issue as an idir\analyst: check the default Effective date and whether the form can be saved after it is cleared. Done means the field defaults to null in yyyy-mm-dd form and a transaction saves successfully without an effective date.

Written by the indexing model from the issue text.