[ADD] filter_appointment: add advanced filters to appointment listing page

[kame-odoo]

This commit adds new filtering options to the website appointment page, improving the user experience by allowing visitors to filter appointments by type (online/offline), payment requirement, and scheduling method (users/resources). A custom controller extends the base WebsiteAppointment to dynamically build a filter domain based on user input and combine it with the standard appointment domain logic. In UI part, the website_calendar_index_topbar template is extended to include three dropdowns that submit on change, making the filtering seamless.

[robodoo]