Add Webhook Feature for Cryptocurrency Price Alert Notifications

[hschickdevs]

Overview: Aim to enhance the bot's capabilities by introducing a webhook feature. This will allow the bot to send a web request to a user-specified URL when an alert is triggered.

Specification: The webhook URL and content could be specified as optional parameters when the alert is created. This would allow people to integrate the bot into their existing trading systems.

Implementation Example: /new_alert <... params ...> webhook_url=https://www.example.com webhook_content={"trigger": "RSI14", "value": 500}