refactored AssetManager

src/extensions/cellpack/model.ts

src/extensions/rcsb/validation-report/prop.ts

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

src/mol-plugin-state/builder/data.ts

src/mol-plugin-state/transforms/data.ts

src/mol-plugin-ui/controls/parameters.tsx

src/mol-plugin/behavior/static/state.ts

src/mol-plugin/context.ts

src/mol-plugin/util/asset-manager.ts

src/mol-util/assets.ts

src/mol-util/data-source.ts

src/mol-util/param-definition.ts