[17.0][ADD] pos_loyalty_card_fixed_expiration_date: New module pos_loyalty_card_fixed_expiration_date

[BernatObrador]

This module introduces the ability to set a fixed expiration date for gift cards.

Follow these steps to configure and use the module:

1. Navigate to Point of Sale -> Products -> Gift Cards & eWallet.
2. Create a new record and set the Program Type to Gift Card.
3. Specify the Duration Days.
4. Generate gift cards without setting an expiration date.
   • The generated gift cards will automatically have an expiration date set to today's date + Duration Days.
5. If you manually set an expiration date, the system will use this specified date instead.

cc https://github.com/APSL 165899

@miquelalzanillas @lbarry-apsl @mpascuall @peluko00 @javierobcn @ppyczko please review

[peluko00]

LGTM! Code review and tested in runboat

[mpascuall]

LGTM, tested in runboat and reviewed code

[ppyczko]

LGTM!

[OCA-git-bot]

This PR has the approved label and has been created more than 5 days ago. It should therefore be ready to merge by a maintainer (or a PSC member if the concerned addon has no declared maintainer). 🤖