[MIG] complete migration of special methods like `init`

addons/decimal_precision/models/decimal_precision.py

addons/hr_timesheet_attendance/models/hr_timesheet_sheet.py

...sheet_attendance/report/hr_timesheet_attendance_report.py

addons/mail/models/mail_channel.py

addons/mail/models/mail_message.py

addons/project_issue/report/project_issue_report.py

addons/stock/models/stock_move.py

..._questions/report/report_event_registrations_questions.py

addons/website_form/models/models.py

addons/website_forum/models/forum.py