This is a start to have different kinds of notifications. It is
possible to be notified via e-mail, matrix or gotify. It also extends
the current "periodic query" for due items by allowing notification
over different channels. A "generic periodic query" variant is added
as well.
Currently the query implementation cannot combine multiple/nested
fulltext searches within a query. It doesn't seem useful to have
shares based on fulltext searches, so it is disabled for now.
Issue: #446
The join to retrieve the attachment count per item turned out to be
very expensive. And it is not used anymore for the result, only to
support fulltext search. It is now removed from the query. The
DISTINCT keyword is also removed, because it is not necessary and it
is expensive. With the DISTINCT removed, a new index (provided in the
previous commit) can now be used to avoid sorting items.
The query now searches in more fields. For example, when getting a
list of tags, the query is applied to the tag name *and* category.
When listing persons, the query now also looks in the associated
organization name.
This has been used to make some headers in the meta data tables
clickable to sort the list accordingly.
Refs: #965, #538
The upload request can now contain a boolean for importing only
attachments when e-mails are uploaded. This option is now also added
to a source url.
Refs: #983
Also hard delete the remaining items. They are empty (have no
attachments), because data is moved if possible. Doesn't make much
sense to keep them, because restoring them isn't much useful.
