More CIF writer refactoring

src/apps/cif2bcif/converter.ts

src/apps/cif2bcif/field-classifier.ts

src/apps/combine-mmcif/index.ts

src/apps/domain-annotation-server/mapping.ts

src/apps/domain-annotation-server/utils.ts

src/mol-io/writer/cif.ts

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

src/perf-tests/cif-encoder.ts

src/servers/model/server/query.ts

src/servers/volume/server/query/encode.ts