[#24] Client: Implement pool part1

first iteration - base classes and methods

Signed-off-by: Pavel Gross <p.gross@yadro.com>

src/FrostFS.SDK.ClientV2/Services/AccountingServiceProvider.cs

@@ -0,0 +1,40 @@
+using System.Threading.Tasks;
+
+using FrostFS.Accounting;
+
+namespace FrostFS.SDK.ClientV2;
+
+internal sealed class AccountingServiceProvider : ContextAccessor
+{
+    private readonly AccountingService.AccountingServiceClient? _accountingServiceClient;
+
+    internal AccountingServiceProvider(
+        AccountingService.AccountingServiceClient? accountingServiceClient,
+        EnvironmentContext context)
+        : base(context)
+    {
+        _accountingServiceClient = accountingServiceClient;
+    }
+
+    internal async Task<Decimal> GetBallance(PrmBalance args)
+    {
+        var ctx = args.Context!;
+
+        BalanceRequest request = new()
+        {
+            Body = new()
+            {
+                OwnerId = ctx.OwnerId!.OwnerID
+            }
+        };
+
+        request.AddMetaHeader(args.XHeaders);
+        request.Sign(ctx.Key!);
+
+        var response = await _accountingServiceClient!.BalanceAsync(request, null, ctx.Deadline, ctx.CancellationToken);
+
+        Verifier.CheckResponse(response);
+
+        return response.Body.Balance;
+    }
+}