Support for RAK5801 4-20mA analog sensor module?

[BentBanana]

Feature Proposal

I've implemented and tested support for the RAK5801 4-20mA sensor module for industrial/agricultural monitoring.

Use Case

• Water level monitoring (currently deployed on farm)
• Works with any 4-20mA sensor (pressure, flow, soil moisture, etc.)
• Reports raw current values for user-side conversion

Implementation Details

• Follows existing TelemetrySensor pattern (similar to BME680, INA219)
• Simple ADC reading, no external dependencies
• Tested and working in production
• Clean, documented code ready

Question

Would this be a welcome contribution? The RAK5801 is official RAK Wireless hardware and fills the gap for analog sensor support.

Happy to submit a PR if there's interest!

[Pearo]

Just started looking for something like this for my farm.