update shards count in dal commitment status (baking-bad#23)

* Add ShardsAttested and Attested (bool) field in DalCommitmentStatus

* update cumulative attestations received from all bakers for a Dal commitment

* Add API endpoints for cumulative DAL commitment status

* Use cache services for dalcommitmentstatus in UpdateDalCommitmentStatus

* Cache the dal attestation data for this level.

* Revert status update made to DalCommitmentStatus due to this block.

Tzkt.Api/Models/Dal/DalCommitment.cs

@@ -21,5 +21,15 @@ public class DalCommitment
         /// Information about the account who has published the commitment.
         /// </summary>
         public Alias Publisher { get; set; }
+
+        /// <summary>
+        /// Total number of Shards attested by the delegates for this commitment
+        /// </summary>
+        public int ShardsAttested { get; set; }
+
+        /// <summary>
+        /// Attestation successful for the commitment
+        /// </summary>
+        public bool Attested { get; set; }
     }
 }