New RTSP Server library

[rjsachse]

I was creating an RTSP server for this project ESP32-CAM_MJPEG2SD (Not yet implemented) and realised it would be even more useful as a library so it can be easily integrated into other projects. The RTSP Server library enables you to stream Video, Audio, and Subtitles all in one RTSP stream. It supports UDP, TCP, and Multicast, though currently is limited to one client at a time. TCP is slower than UDP, Unicast, or Multicast, but all options are available for flexibility. This initial release was quickly put together before I returned to work, with plans for further optimization. Only tested on my own esp32s3 custom board.

Try out the example and explore the capabilities of the RTSP Server library here: RTSPServer

[rzeldent]

Duplicate of #155