UnknownRntbdHeader : Adds a new SDK capability for UnknownRntbdHeaders (#5127)

Adding support for accepting unknownRntbd headers from backend.

- [] Bug fix (non-breaking change which fixes an issue)

Co-authored-by: Kiran Kumar Kolli <kirankk@microsoft.com>
Co-authored-by: Debdatta Kunda <87335885+kundadebdatta@users.noreply.github.com>

Author: 3 people

Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.EmulatorTests/ClientTests.cs

@@ -402,7 +402,7 @@ public async Task TestHeadersPassedinByClient()
             string sdkSupportedCapability = sdkSupportedCapabilities.Single();
             ulong capability = ulong.Parse(sdkSupportedCapability);
 
-            Assert.AreEqual((ulong)SDKSupportedCapabilities.PartitionMerge, capability & (ulong)SDKSupportedCapabilities.PartitionMerge,$" received header value as {sdkSupportedCapability}");
+            Assert.AreEqual((ulong)(SDKSupportedCapabilities.PartitionMerge | SDKSupportedCapabilities.IgnoreUnknownRntbdTokens), capability & (ulong)(SDKSupportedCapabilities.PartitionMerge | SDKSupportedCapabilities.IgnoreUnknownRntbdTokens), $"received header value as {sdkSupportedCapability}");
         }
 
         [TestMethod]

Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/Contracts/ContractTests.cs

@@ -29,7 +29,7 @@ public void ApiVersionTest()
             CollectionAssert.AreEqual(Encoding.UTF8.GetBytes(HttpConstants.Versions.v2020_07_15), HttpConstants.Versions.CurrentVersionUTF8);
 
             ulong capabilitites = SDKSupportedCapabilitiesHelpers.GetSDKSupportedCapabilities();
-            Assert.AreEqual(capabilitites & (ulong)SDKSupportedCapabilities.PartitionMerge, (ulong)SDKSupportedCapabilities.PartitionMerge);
+            Assert.AreEqual((ulong)(SDKSupportedCapabilities.PartitionMerge | SDKSupportedCapabilities.IgnoreUnknownRntbdTokens), capabilitites & (ulong)(SDKSupportedCapabilities.PartitionMerge | SDKSupportedCapabilities.IgnoreUnknownRntbdTokens));
         }
 
         [TestMethod]