Remove destroy(:force) methods from all equipment

[dgoerger]

Currently one can still destroy(:force) (i.e., hard-delete) Categories, Equipment Models, and Equipment Objects. Doing so hard-deletes all associated reservations.

We already encourage deactivation in the equipment index pages; we should do the same for the show/edit pages, and remove the ability to hard-delete equipment, so that the admin can't so easily destroy reservation history / logs.

If there are any more destroy(:force) methods in the code, we should reconsider these as well.

[dgoerger]

merged to release-v3.4 in #817.

still due for master.