Removed Unit.label, fixed Model.label from mmCIF

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

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

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

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

src/perf-tests/lookup3d.ts

src/servers/model/server/api.ts

src/servers/model/server/query.ts