file-xfer: move debug to SpiceFileTransferTask
file-xfer: move debug to SpiceFileTransferTask

This debug information is simple way to check that the file-transfer
is not stalled. Now that we are using the read-async functions, we can
move this debug info there and avoid accessing object internals in
channel-main.c

Acked-by: Jonathon Jongsma <c7254805a17bd5c41e24c3a278fcbf3afcdfb0fa@redhat.com>

fgouget/spice-gtk,flexVDI/spice-gtk,fgouget/spice-gtk,fgouget/spice-gtk,flexVDI/spice-gtk