Add a configuration for max-bitrate
Re-purposed from initial issue:
UDP streams with large I-frames (4K ip-cameras and even some 1080p) are generating too large UDP burst and those will be dropped by routers/VPN GWs etc. with small buffers (datacenter connections are 10Gbits but Internet only 100Mbits).
While it's theoretically possible through GstBin::deep-element-added signal to do custom setup on the udpsink, it is likely that these days more and more users will need to control the burst rate. The buffer-size has been exposed similarly if I read the code correctly.