Discord rich presence feature implementation

[waveyboym]

Implementation of discord rich presence:

1. I made use of the discord-rich-presence crate using version 0.2.3
2. All of the code for the RPC API is found in discord_rpc which acts as an API wrapper and only exposes certain functions that will be needed by the frontend, namely:

allow_connection_and_connect_to_discord_rpc,
attempt_to_connect_if_possible, 
disallow_connection_and_close_discord_rpc,
set_discord_rpc_activity, 
clear_discord_rpc_activity

3. The functionality of discord rpc has been tested and shows that it is stable and works well enough.
4. A dotenv crate was also added to store the client_id for discord in dev environments without uploading it to github, however when a production build is made, the client_id can just be embedded in the source code if building with an env variable fails.

A production build is yet to be tested but will be tested before this pr is merged with main-app-dev