made `State` a generic type parameter for Representations

src/mol-repr/representation.ts

src/mol-repr/structure/complex-representation.ts

src/mol-repr/structure/registry.ts

src/mol-repr/structure/representation.ts

src/mol-repr/structure/representation/ball-and-stick.ts

src/mol-repr/structure/representation/carbohydrate.ts

src/mol-repr/structure/representation/cartoon.ts

src/mol-repr/structure/representation/distance-restraint.ts

src/mol-repr/structure/representation/molecular-surface.ts

src/mol-repr/structure/representation/molecular-volume.ts

src/mol-repr/structure/representation/point.ts

src/mol-repr/structure/representation/spacefill.ts

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

src/mol-repr/volume/registry.ts

src/mol-repr/volume/representation.ts