[Feature] the number of documents in a collection Retrieve logic implementation.

[Feature]

• Retrieve the number of documents in a collection using aggressive query logic implement in request(endpoint:)
  • It execute to retrieve the number of all documents in a specified collectionRef from FirestoreAccessible.
  • This method using AggrateQuery's count() that match between 0 and 1000 index entries billed for one documen read: ]

• Set Endpoint's responseDTO's type Int and FirestoreAccessible must return CollectionReference without DocumentReference and then use this method: ]

[References]

• official Document aggregation-queries link
• official Document AggregateSource link
• stackOverflow Cloud Firestore collection count