NEC-TM: filter top-level-categories when creating a NEC-TM-LanguageResource

When creating NEC-TM LanguageResource, please do not include the tags that are set as runtimeOptions.plugins.NecTm.topLevelCategoriesIds in the categories-list. They are used anyway, so it's only confusing to be able to choose them here.

Note: Categories must not be empty! (If no topLevelCategoriesIds are set, at least one category must be chosen when creating a NEC-TM. If topLevelCategoriesIds are set, choosing further categories from the list is optional.)