Set target bitrate without reinitialize

[algesten]

This adds a set_target_bitrate on the Encoder, which means the bitrate can be altered while the encoder is running and not just at init time.

[ralfbiedert]

Thanks! Small nit, should this be called set_bitrate since that's what it is in the Config already?

[ralfbiedert]

Ah, could you also add a small test triggering this between two frames while the encoder is initialized?

[algesten]

Will do! (on both)

[algesten]

I've hit problems. Setting the bitrate on the fly is giving me an error in the test setup. But I could have sworn this is how we do it in our branch of openh264-rs. I need to investigate if we never hit that code path, and this indeed is not going to work.

[ralfbiedert]

I'm closing this as stale for now. Feel free to re-open if there is new progress.