[Feature]: Passing secrets via JVM Properties

### 🚀 Description

Could you please consider making the bot check for secrets (bot token, webhooks) in JVM properties on startup so they can be loaded from an `env.properties` file for example (launch logic would handle the property loading, not sdlink)? This would be an alternative to storing them in the config file.

Context: [Support thread](https://discord.com/channels/750990873311051786/1469462433541259295)

### 💡 Use Case

Example use cases
- Server configuration versioned in git and deployed using CI/CD
- Bad practice to store secrets in version control, so preferable to keep them in an environment file on the server
- A server network where multiple servers are deployed with the same configuration, but each require a unique set of secrets (Suggested by Kaleidio)

Start at the bot's startup and launch logic, then review how secrets are currently loaded from the config file. Define how bot tokens and webhooks should be supplied through JVM properties or an env.properties file, while keeping property loading outside sdlink; done means both secret types can be provided without storing them in the config file.

Written by the indexing model from the issue text.