Evaluate a replacement for `bootstrap-datepicker` and `bootstrap-daterangepicker`

[maliming]

bootstrap-datepicker pins jquery >=3.4.0 <4.0.0 and calls $.isArray, $.isFunction and $.proxy; upstream is barely maintained. The bootstrap-daterangepicker source we ship was last published in 2020.

Both are used in many places, so we should pick a replacement (flatpickr, tempus-dominus, or the native date input) before changing anything.

Part of #25123.