[FIX] ir_attachment: hide Attachments > Add/Delete if not write access

To be able to see record attachments, you need to have
read access to the record.

To be able to add or delete attachment, you need to
have write access to the record.

The button add/delete were displayed as soon
as you had the read access, but if you had not the
write access, both buttons failed.

This revision do not display the add/delete
buttons of Attachment dropdown menu if you do not
have the right to add / delete attachments to the record
(you do not have write access to the record)

opw-640242