Add ability in stream to modify video codec framerate

[shubhamfuloria]

Openh264 codec supports dynamic change of bitrate and framerate. This pull request contains functionality with which we can modify framerate of encoding stream after the codec is open with SetOption API of openh264.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}