[account_document_reversal] Add option for reversal only if date is out current month

[celm1990]

Hi guys, i tested this module and is wonderful, i see a possible feature to be implemented.

current configuration on journal on field cancel_method is: normal(cancel document) reversal(reversal is done independet of document date and back to draft is blocked always )

I sugges add option(name can be better) reversal_by_month(reversal only if month of document date is not same to current month)

So, if journal has set option reversal_by_month:

1. if document date is same month of current month, Button back to draft is not restrictive and can be cancel document normaly

2. Based on same configuration, if document date is not same month to current month show wizard for reversal and working as current reversal option

I can create a draft PR with feature for V12 and 13, what do you think??? Thank for your comments