Add confirmation dialog when we delete a subscriber of Bioscurity

[qifeng-bai]

Where if you try to copy and paste an email address of a subscriber, it detects any mouse event on it and deletes that subscriber. It needs a confirmation to say “Are you sure you want to remove this email address…

Also added: Only clicking the delete icon will trigger the deletion.

[nickdos]

When you "hover" over the delete icon, there is no "feedback" to indicate the icon is a clickable element. I.e. the mouse icon remains an"arrow" and not the expected "hand" (pointer) cursor. See

<i onclick="unsubscribe(268, 142,'nick.dosremedios@csiro.au')" class="fas fa-trash"></i>

This should be changed to either a <a href=... or <button... element so that the user is clear that the element is "clickable".

[qifeng-bai]

Added a hand pointer for all clickable items