DevMgr: Add attachAllUnattachedDevicesFromKnownListReq

This function is the backbone for the DeviceReattacher daemon. It
assembles a list of all DA specs which are known to Mrntt, but which
haven't been successfully attached as yet, and attempts to attach
them.

smocore/deviceManager/deviceManager.cpp

@@ -584,6 +584,38 @@ void DeviceManager::attachAllUnattachedDevicesFromCmdlineReq(
 	attachAllUnattachedDevicesFromReq(specs, std::move(cb));
 }
 
+void DeviceManager::attachAllUnattachedDevicesFromKnownListReq(
+	Callback<attachAllUnattachedDevicesFromReqCbFn> cb
+	)
+{
+	// Create a vector to hold unattached device specs
+	auto unattachedSpecs = std::make_shared<std::vector<DeviceAttachmentSpec>>();
+
+	// Cycle through all DA specs in deviceAttachmentSpecs
+	for (const auto& spec : deviceAttachmentSpecs)
+	{
+		bool isAttached = false;
+
+		// Cross reference with attachedDeviceRoles
+		for (const auto& role : attachedDeviceRoles)
+		{
+			if (*role->deviceAttachmentSpec == *spec)
+			{
+				isAttached = true;
+				break;
+			}
+		}
+
+		// If spec doesn't appear in attachedDeviceRoles, add it to the vector
+		if (!isAttached) {
+			unattachedSpecs->push_back(*spec);
+		}
+	}
+
+	// Pass the vector to the existing function
+	attachAllUnattachedDevicesFromReq(unattachedSpecs, std::move(cb));
+}
+
 class DeviceManager::DetachAllAttachedDeviceRoles
 :	public PostedAsynchronousContinuation<
 		detachAllAttachedDeviceRolesCbFn>