[ADD]pms: Self billing folios configuration

[DarioLodeiros]

Enhancements to the billing process by adding support for self-billed journals and taxes. The changes ensure that the system correctly applies self-billed journals and taxes when the partner is the same as the company partner.

Key changes include:

Self-billing support:

• Added self_billed_journal_id and self_billed_tax_ids fields to the ResCompany model to store the self-billed journal and taxes information.

Invoice and tax computation:

• Updated _get_folio_default_journal method in pms_property.py to return the self-billed journal if the partner is the company partner.
• Modified _compute_tax_ids method in pms_reservation.py to check for self-billed taxes when the partner is the company partner.
• Enhanced _compute_tax_ids method in pms_service.py to apply self-billed taxes when the service partner is the company partner.