Move test data for icalendar tests to separate files.
* test/lisp/calendar/icalendar-tests.el
(icalendar-tests--data-dir, icalendar-tests--get-file-contents):
New.
(icalendar-tests--test-import, icalendar-tests--do-test-import):
Read input and expected results from files.
(icalendar-import-non-recurring, icalendar-import-rrule)
(icalendar-import-duration, icalendar-import-bug-6766)
(icalendar-import-bug-24199, icalendar-import-bug-33277)
(icalendar-import-multiple-vcalendars, icalendar-import-with-uid)
(icalendar-import-with-timezone, icalendar-real-world): Move test
data (input and expected result) to separate files.
* test/calendar/icalendar/*
New files containing test data for icalendar tests.