DevMgr: Add DeviceRoles; attachedDevices unrelated to device state now

We've decided to add a separate notion of a DeviceRole to track attached
device roles now. We no longer use the collection of deviceSpecs to
track which roles have been attached. Rather, this list will simply
collate all known deviceAttachment specs which are expected to be
maintained in an attached state.

SMO can periodically scan through these and cross-reference this
collection with the collection of attachedDeviceRoles. Then it can
re-try to attach those which aren't currently attached at any given
moment. This will give resilience against device attachment failures
or device resets/malfunctions, at runtime.

smocore/include/deviceManager/device.h

@@ -6,6 +6,7 @@
 #include <memory>
 #include <sstream>
 #include <user/deviceAttachmentSpec.h>
+#include <deviceManager/deviceRole.h>
 
 namespace smo {
 namespace device {
@@ -19,16 +20,16 @@ public:
     {
         std::ostringstream os;
         os << "Device Identifier: " << deviceIdentifier
-           << ", Attachment Specs: " << deviceAttachmentSpecs.size() << std::endl;
-        for (const auto& spec : deviceAttachmentSpecs) {
-            os << "  " << spec->stringify();
+           << ", Device Roles: " << deviceRoles.size() << std::endl;
+        for (const auto& deviceRole : deviceRoles) {
+            os << "  " << deviceRole->deviceAttachmentSpec->stringify();
         }
         return os.str();
     }
 
 public:
 	std::string deviceIdentifier;
-	std::vector<std::shared_ptr<DeviceAttachmentSpec>> deviceAttachmentSpecs;
+	std::vector<std::shared_ptr<DeviceRole>> deviceRoles;
 };
 
 } // namespace device