OwrImageRenderer: Add a queue to decouple conversion from decoding

Previously there was one thread from the jitterbuffer through to the
sink. Use max-size-buffers = 3 as the limiting factor to allow a bit of
scheduling room.
owr_utils: Remove chatty and not-useful pipeline debug log

This is too hard to read and dot graphs are much easier to use.
OwrImageRenderer: Compare double max framerate to 0.0, not 0
OwrVideoRenderer: Fix queue max-size-time guint64 property
OwrTransportAgent: Fix queue properties

max-size-time is a guint64 so the constant needs to also be
G_GUINT64_CONSTANT()-ified. Also set max-size-buffers to 3 to give a bit
of scheduling room.