[18.0][ADD] hr_holidays_allocation_domain

[etobella]

With this module, we are able to filter using complex domains on the allocation generation.

[pedrobaeza]

The module name should be prefixed by hr_holidays, so hr_holidays_allocation_domain may be a good candidate.

[etobella]

@pedrobaeza comments attended 😉

[github-actions]

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[luisDIXMIT]

Code review and tested locally, LGTM!