Support for the ClimateGuard RadSens Geiger-Muller tube

[jake-b]

This PR is to support the ClimateGuard RadSense dosimeter.
This is an I2C device which integrates nicely into the firmware along side other sensors.

• Added radiation to EnvironmentMetrics to hold the measurement in micro-roentgen
• Added RADSENS to TelemetrySensorType

These changes will support a future pull request to the meshtastic firmware to add support for this device.

Thanks for your consideration.

Checklist before merging

• All top level messages commented
• All enum members have unique descriptions

[CLAassistant]

All committers have signed the CLA.

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