mol-state: better typing for cells and selections

src/apps/basic-wrapper/index.ts

...dynamic/selection/structure-representation-interaction.ts

src/mol-plugin/skin/base/components/transformer.scss

src/mol-plugin/skin/base/icons.scss

src/mol-plugin/state/actions/structure.ts

src/mol-plugin/state/animation/built-in.ts

src/mol-plugin/ui/controls.tsx

src/mol-plugin/ui/state.tsx

src/mol-state/action.ts

src/mol-state/object.ts

src/mol-state/state.ts

src/mol-state/state/builder.ts

src/mol-state/state/selection.ts

src/mol-state/transform.ts

src/mol-state/transformer.ts