New client node data pull from server

Dear @egarim

I appreciate your hard work. I found it an excellent sync library. I have seen all of your videos regarding the sync framework.
The Unit test is not depicting all the scenarios. Please consider the following procedure.

Let's say I have a client node connected to the server with Identity = store 1. The client syncs all its data to the server. Somehow client one crashed/lost their data, or I want the same data to be synced on 2nd device, or a fresh client with the same Identity want to restore data. It is working fine, but It does not sync its data; it syncs all other data. I have seen the code in `ISyncServerNode,` which fetches deltas for other Nodes.
```
public class SyncServerNode : ISyncServerNode
{
...
public virtual Task> GetDeltasAsync(Guid startindex, string identity, CancellationToken cancellationToken)
{
return this.deltaStore?.GetDeltasFromOtherNodes(startindex, identity, cancellationToken);
}
...
```
Look at this code `return this.deltaStore?.GetDeltasFromOtherNodes(startindex, identity, cancellationToken);` It fetches data of other nodes. There should be another function in the `ISyncServerNode.`
```
public interface ISyncServerNode
{
string NodeId { get; set; }
Task SaveDeltasAsync(IEnumerable deltas, CancellationToken cancellationToken);
Task> GetDeltasFromOtherNodesAsync(Guid startindex, string identity, CancellationToken cancellationToken);
Task> GetDeltasAsync(Guid startindex, CancellationToken cancellationToken);
Task ProcessDeltasAsync(IEnumerable deltas, CancellationToken cancellationToken);
}
```
There should be two functions like
```
Task> GetDeltasFromOtherNodesAsync(Guid startindex, string identity, CancellationToken cancellationToken);
Task> GetDeltasAsync(Guid startindex, CancellationToken cancellationToken);
```
One should be used for the normal operation scenario, and the 2nd should be used in case of a fresh/new/crashed node. Similarly, the `SynController` Fetch function should also be updated with NodeId and without NodeId or another filter header.

Thank you,
Qamar Abbas