ui/util/firestore_checkbox library

1. fm_firestore package
2. documentation
3. ui/util/firestore_checkbox.dart

fm_firestore package

1. Libraries
2. coll/fire_coll
3. coll/fire_coll_query
4. converters/firestore_date_time_converter
5. converters/firestore_date_time_pass
6. doc/fire_doc
7. doc/fire_doc_tuple
8. fm_firestore
9. ui/query_builder
10. ui/util/firestore_checkbox