connectionmanager: add isConnected

To check if we're connected with a device

Change-Id: I9d0659c3d6d5e305baabd5c4156a820754bae377
diff --git a/src/connectionmanager.cpp b/src/connectionmanager.cpp
index 5474fa0..87704a8 100644
--- a/src/connectionmanager.cpp
+++ b/src/connectionmanager.cpp
@@ -1883,6 +1883,16 @@
     return false;
 }
 
+bool
+ConnectionManager::isConnected(const DeviceId& deviceId) const
+{
+    if (auto dinfo = pimpl_->infos_.getDeviceInfo(deviceId)) {
+        std::unique_lock<std::mutex> lk {dinfo->mtx_};
+        return dinfo->getConnectedInfo() != nullptr;
+    }
+    return false;
+}
+
 void
 ConnectionManager::closeConnectionsWith(const std::string& peerUri)
 {