Rework get_queue_by_flags function so it can select a dedicated transfer queue if requested

Currently, when you ask for a transfer queue, for example, you would get the first queue that supports transfer, which probably is the same as you get when asking for graphics support.
When a dedicated transfer queue can be requested and is used (in the gltfLoader, for example), ownership of uploaded data needs to be handled properly. And a separate CommandPool would be needed for the CommandBuffer submitted to that queue.

Start by locating get_queue_by_flags and the gltfLoader use of a transfer queue. Trace how queue-family ownership is handled for uploaded data and how the submitted CommandBuffer gets its CommandPool. Done means a dedicated transfer queue can be selected when requested, with ownership handled correctly and a separate CommandPool used for that queue.

Written by the indexing model from the issue text.