Add or remove streamer on runtime.

[AI-Maria]

Is your feature request related to a problem?

I need a feature to join and leave channels at runtime without restarting (e. g. fetch followed channels once per day and update streamers). Also it can be needed for #540 ( #621 ) - get live streamers from category and join to them.

Proposed solution

Refactor mine and end methods inside TwitchChannelPointsMiner class. Make methods add_streamer, remove_streamer.

Alternatives you've considered

No response

Additional context

No response