split SharingSidebar into a few separate components (#15203)

* split SharingSidebar into a few components

* rmv emailRecipientText prop (unused)

* use pulse.id in place of pulseId

* use _.partial to avoid passing index prop

* cut a few lines of code

* add minor comment for components with too many props

* add proptypes to new components and fix key errs

* move time formatting utils

* add handling for 12pm

Co-authored-by: flamber <1447303+flamber@users.noreply.github.com>

Co-authored-by: flamber <1447303+flamber@users.noreply.github.com>