split up StructureElement

src/apps/structure-info/model.ts

src/examples/proteopedia-wrapper/coloring.ts

src/mol-model-formats/structure/mmcif/bonds/comp.ts

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

src/mol-model-props/pdbe/structure-quality-report.ts

src/mol-model-props/pdbe/themes/structure-quality-report.ts

src/mol-model-props/rcsb/themes/assembly-symmetry-cluster.ts

src/mol-model/location.ts

src/mol-model/loci.ts

src/mol-model/structure/export/categories/atom_site.ts

...ol-model/structure/export/categories/modified-residues.ts

...-model/structure/export/categories/secondary-structure.ts

src/mol-model/structure/model/properties/custom/indexed.ts

src/mol-model/structure/query/context.ts

src/mol-model/structure/query/queries/filters.ts

src/mol-model/structure/query/queries/internal.ts

src/mol-model/structure/query/utils/builders.ts

src/mol-model/structure/structure/element.ts

src/mol-model/structure/structure/element/element.ts

src/mol-model/structure/structure/element/index.ts