Add CMDTYPEs for dealing with features

The only `CMDTYPE` that can take features as an argument is `ICON_UNIT_FEATURE_OR_AREA`. This is a problem for skyrbunny, who wants to make Warcraft 3-style items, and is thinking of making the items be features. We should have everything for features that we have for units. So `ICON_FEATURE`, `ICON_FEATURE_OR_MAP`, `ICON_FEATURE_OR_AREA`, and (I suppose), `ICON_FEATURE_OR_RECTANGLE`.

Just look at how inbuilt resurrect is implemented, a command that should be `ICON_FEATURE_OR_AREA`:

Start by locating the CMDTYPE definitions and the inbuilt resurrect command mentioned in the issue. Compare the existing unit feature-related command types, then add the requested feature variants: ICON_FEATURE, ICON_FEATURE_OR_MAP, ICON_FEATURE_OR_AREA, and ICON_FEATURE_OR_RECTANGLE. Done means feature-based items can use the same command coverage as units.

Written by the indexing model from the issue text.