Use Discord IPC / RPC for Rich Presence instead of external library

Describe your suggested feature

Current:

• Kotatsu relies on an external library called KizzyRPC (build ad8f2e32eb) for this feature to work.
• Users frequently receive password reset emails due to Discord suspecting that their tokens have been leaked even though that hasn't happened. In fact, KizzyRPC will use the user's account as a Self-bot through websocket, which is illegal and not allowed on Discord (based on their terms of use).

Solution:

• Completely remove KizzyRPC (external library)
• Implement connection to Discord IPC and send out watching activity from Kotatsu.

Result:

• Reduce the original size of the packaged application.
• Users don't need to log in or type Discord token to make this feature work on Kotatsu.

Reference:

• Discord IPC / RPC didnt exist on Android, i found this repository for creating Discord IPC: caoimhebyrne/KDiscordIPC but can't implement it on Android.

Acknowledgements

• This is not a duplicate of an existing issue. Please look through the list of open issues before creating a new one.