[Feature request] Add replay buffer button

[Niek]

From the discussions:

Would it be possible to add the replay buffer button to this?

Originally posted by @Cman1239 in #98

[Niek]

Relevant docs:

5.x: https://github.com/obsproject/obs-websocket/blob/master/docs/generated/protocol.md#getreplaybufferstatus
4.x: https://github.com/obsproject/obs-websocket/blob/4.x-compat/docs/generated/protocol.md#replay-buffer-1

[Niek]

Implemented by @filiphanes - thanks a lot!