feat: add type-safe alternative to `_add_holiday_*` methods

[williambdean]

The _add_holiday_* methods lack of type completion makes use quite difficult. They are documented here:

https://github.com/vacanza/holidays/blob/8bd401812e1f200316737c3622fd380869bf74ff/docs/examples.md?plain=1#L414-L432

Pandas provides an interface to create calendars from holidays which leverage offset and observance parameters.

Reference: https://pandas.pydata.org/docs/user_guide/timeseries.html#holidays-holiday-calendars

Related to: https://github.com/vacanza/holidays/pull/2721 https://github.com/vacanza/holidays/discussions/1665