feat(fields,app-shell,plugin-list): 「is empty」 / 「is not empty」 builders write the spec's one operator $empty; fields and app-shell floor at @objectstack/spec ^17.6.0 (objectui#10813)

feat(fields,app-shell,plugin-list): 「is empty」 / 「is not empty」 builders write the spec's one operator $empty; fields and app-shell floor at @objectstack/spec ^17.6.0 (objectui#10813) #12177