Clean up `SchedulePicker` component (#26839)

* Move `SchedulePicker` to its own directory

* Sort imports

* Do basic clean up

* Extract `DEFAULT_DAY` to a constant

* Extract styled components

* Convert `SchedulePicker` to TypeScript

* Add `SchedulePicker` container

* Export `SchedulePicker` options

* Add basic `SchedulePicker` story

* Fix `SchedulePicker` crashes Storybook

* Tweak Storybook file