(maint) Ignore CA1416 warnings

With Visual Studio 2026 installed, warnings are treated as errors, and
there are a few places that this warning is emitted. This wraps those
locations with pragma warning disable statements so that the build
succeeds.

Author: corbob

src/NuGet.Core/NuGet.Packaging/Signing/Authoring/SignPackageRequest.cs

@@ -98,7 +98,9 @@ protected virtual void Dispose(bool disposing)
                 Chain?.Dispose();
 
 #if IS_SIGNING_SUPPORTED
+#pragma warning disable CA1416
                 PrivateKey?.Dispose();
+#pragma warning restore CA1416
 #endif
             }
 

src/NuGet.Core/NuGet.Packaging/Signing/Cms/NativeUtility.cs

@@ -120,7 +120,9 @@ internal unsafe static CMSG_SIGNER_ENCODE_INFO CreateSignerInfo(
 
             signerInfo.cbSize = (uint)Marshal.SizeOf(signerInfo);
             signerInfo.pCertInfo = MarshalUtility.PtrToStructure<CERT_CONTEXT>(cmsSigner.Certificate.Handle).pCertInfo;
+#pragma warning disable CA1416
             signerInfo.hCryptProvOrhNCryptKey = privateKey.Handle.DangerousGetHandle();
+#pragma warning restore CA1416
             signerInfo.HashAlgorithm.pszObjId = cmsSigner.DigestAlgorithm.Value;
 
             if (cmsSigner.SignerIdentifierType == SubjectIdentifierType.SubjectKeyIdentifier)