Update the Search dialog when items in the calendar change

When `CalendarView::slotModifyFinished` fires, the calendar has not been
updated, so the `calendar()->events` call in `SearchDialog::updateView`
returns stale events.  This patch connects `SearchDialog::updateView` to
the `calendarChanged` signal, which is what is done for the Event List.
1 job for release/21.08 in 2 minutes and 13 seconds (queued for 2 seconds)
Status Name Job ID Coverage
failed build_clazy_clang_tidy #128684


Name Stage Failure
build_clazy_clang_tidy Build
11 warnings generated.
make[1]: *** [CMakeFiles/Makefile2:788: src/CMakeFiles/korganizer_core.dir/all] Error 2
make: *** [Makefile:146: all] Error 2
Uploading artifacts for failed job
Uploading artifacts...
WARNING: JUnitTestResults.xml: no matching files
ERROR: No files to upload
Cleaning up file based variables
ERROR: Job failed: exit code 1