wip, createOrUpdate method for representations and visuals

src/apps/canvas/app.ts

src/apps/canvas/component/app.tsx

src/apps/canvas/component/structure.tsx

src/apps/canvas/index.ts

src/apps/canvas/structure-view.ts

src/mol-geo/representation/index.ts

src/mol-geo/representation/shape/index.ts

...ol-geo/representation/structure/complex-representation.ts

src/mol-geo/representation/structure/complex-visual.ts

src/mol-geo/representation/structure/index.ts

...l-geo/representation/structure/representation/backbone.ts

...representation/structure/representation/ball-and-stick.ts

...o/representation/structure/representation/carbohydrate.ts

...ol-geo/representation/structure/representation/cartoon.ts

...esentation/structure/representation/distance-restraint.ts

src/mol-geo/representation/structure/units-representation.ts

src/mol-geo/representation/structure/units-visual.ts

src/mol-geo/representation/structure/visual/element-point.ts

src/mol-geo/representation/structure/visual/util/common.ts

src/mol-geo/representation/util.ts