Add a "Show hidden fields" link

[Rob Guttman]

Sometimes fields are hidden because most of the time they're not needed and just add noise to ticket views. However, every now and then, it's useful to have access to those hidden fields.

[Rob Guttman]

The approach I'm taking is that fields can be enabled individually to be shown via a new "Show hidden fields" link (which only gets shown when there are in fact hidden fields). The additional rule specification is:

[ticket-custom]
mostlyhidden.show_when_type = enhancement
mostlyhidden.clear_on_hide = false
mostlyhidden.link_to_show = true

The default is that hidden fields are not enabled to be shown (i.e., link_to_show defaults to false).

[Rob Guttman]

(In [9718]) refs #8355: added "show hidden fields" link and facility.

[Rob Guttman]

Done. Docs on wiki page have been updated.

[Steffen Hoffmann]

Awesome, looks really useful (as good as this has started). Thank you very much for your effort. I'll definitely will have to check that out together with the owner field reordering from #8356.