Rework Topic Icons

Currently, we allow for the addition of an icon when creating a topic. We need to rework them to allow for the use of SVG icons pulled in the same manner as the forum imageset icons.

The system needs to be changed so that the icons are loaded based on the title. The title will be used to load the icons based on a new property of type. The type can be either an SVG file, png file, or iconify icon. The setting will be used in the template to check which method should be used and load the icon using the twig icon function based on this setting using the title as the value to load.

exp:

if it is an SVG or png the title could be: "checked-box"

the function would look in the "all/imgs/svg/topic-icons" if its an SVG or "all/imgs/png/topic-icons" if its a png. These would also be where the icons get uploaded through the ACP.

If iconify is selected it will have an additional setting that must be set for library abbreviation.

if it is iconify the title could be: "checked-box" and the library abbreviation could be "mdi"

the function would load the mdi:checked-box" icon using iconify.