Make used of typed atomic.Pointer (#23550)

server/channels/app/platform/config.go

@@ -198,10 +198,7 @@ func (ps *PlatformService) regenerateClientConfig() {
 
 // AsymmetricSigningKey will return a private key that can be used for asymmetric signing.
 func (ps *PlatformService) AsymmetricSigningKey() *ecdsa.PrivateKey {
-	if key := ps.asymmetricSigningKey.Load(); key != nil {
-		return key.(*ecdsa.PrivateKey)
-	}
-	return nil
+	return ps.asymmetricSigningKey.Load()
 }
 
 // EnsureAsymmetricSigningKey ensures that an asymmetric signing key exists and future calls to