Add RAKwireless RAK11300

[nmaas87]

Adding a PR for getting the RAKwireless RAK11300 board into the Arudino Pico environment.
The RAK11300 is a combined board, having a RP2040 and an SX1262 LoRa RF chip included.

Information was scare, but I could find what I needed using:

• https://docs.rakwireless.com/Product-Categories/WisDuo/RAK11300-Module/Datasheet/#description
• https://forum.rakwireless.com/t/rak11300-pinout-rp2040-to-sx1262/8414
• https://github.com/RAKWireless/RAK-RP-Arduino/tree/main
• https://github.com/RAKWireless/RAK11300-AT-Command-Firmware/tree/main/RAK11300-AT-Arduino

The original BSP is only available for Arduino mbedOS - and the repo is quite mangled.

The RAK11300 is basically just an RP2040 with some pins for the SPI1 rearranged to better fit the directly connected SX1262 module - and that were basically the changes I included.

If accepted, this should close: #406

This repo does not contain any examples to use with the LoRa module included and also shall not contain something, as this is part of library for LoRa modules. I am currently trying to get it working with jgromes/RadioLib#864

Best regards and thanks for the awesome work and support of Arduino Pico

Nico

Some additional infos about the whole project in my blog post: https://www.nico-maas.de/?p=2607

[maxgerhardt]

Looking great!

[nmaas87]

Thanks so much 💯

[earlephilhower]

Addin again, thanks @maxgerhardt for the assist!

[nmaas87]

Thank you so much for merging @earlephilhower and @maxgerhardt for the guidelines and support 👍🏻