wip generic atomic custom props

src/mol-model-props/common/custom-element-property.ts

src/mol-model-props/common/custom-property-registry.ts

...ior/dynamic/custom-props/pdbe/structure-quality-report.ts

...n/behavior/dynamic/custom-props/rcsb/assembly-symmetry.ts

src/mol-plugin/context.ts

src/servers/volume/server/local-api.ts