Add support for lowpowerlab's moteino_m4

[vitormhenrique]

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• Feature Request.
  Start by telling us what problem you’re trying to solve. Often a solution
  already exists! Don’t send pull requests to implement new features without first getting our
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Configuration

Operating system: Mac OS Ventura: 13.1 (22C65)

PlatformIO Version (platformio --version): PlatformIO Core, version 6.1.5

Description of problem

Add support for lowpowerlab RFGateway (M4). Also know as moteino_m4.

The pin and hardware definitions are already on framework-arduino-samd-moteino under variants/moteino_m4