Some attachments may not have `contentBytes` property, the same as it can be
quite large file, thus read them one-by-one instead.

Closes https://gitlab.gnome.org/GNOME/evolution-ews/-/issues/267

With help of the code from evolution-mapi to decode recurrence blobs,
read also detached and recognize deleted instances of a recurring
event series.

Be able to modify event series by either modifying single instances or
delete them.