Color Table Tag Export

[JustinPrivitera]

At the moment, if users want to add new tags to a given color table, they must open the associated .ct file and add the tags there. We should make it possible for tags to be edited and exported from the GUI (and the CLI? Can users make color tables on the CLI? - yes, but they probably can't export them. There is a quick-recipe in docs to make color tables on the CLI).