Remove KPIM::Person and related jobs

Summary:
This is an abstraction over LDAP persons and lookup of Collections
that represent personal calendars. This was used only to enrich
the calendar view in KOrganizer.

Test Plan: KDE PIM still compiles

Reviewers: vkrause, dfaure

Reviewed By: vkrause

Subscribers: kde-pim

Tags: KDE PIM

Differential Revision: https://phabricator.kde.org/D20347