STM32: Migrate variants to new structure (#7389)

variants/stm32/rak3172/platformio.ini

@@ -0,0 +1,14 @@
+[env:rak3172]
+extends = stm32_base
+board = wiscore_rak3172
+board_upload.maximum_size = 233472 ; reserve the last 28KB for filesystem
+build_flags =
+  ${stm32_base.build_flags}
+  -Ivariants/stm32/rak3172
+  -DPIN_WIRE_SDA=PA11
+  -DPIN_WIRE_SCL=PA12
+  -DMESHTASTIC_EXCLUDE_ENVIRONMENTAL_SENSOR=1
+  -DMESHTASTIC_EXCLUDE_I2C=1
+  -DMESHTASTIC_EXCLUDE_GPS=1
+  ;-DCFG_DEBUG
+upload_port = stlink

variants/stm32/rak3172/variant.h

@@ -0,0 +1,19 @@
+/*
+STM32WLE5 Core Module for LoRaWAN® RAK3372
+https://store.rakwireless.com/products/wisblock-core-module-rak3372
+*/
+
+/*
+This variant is a work in progress.
+Do not expect a working Meshtastic device with this target.
+*/
+
+#ifndef _VARIANT_RAK3172_
+#define _VARIANT_RAK3172_
+
+#define USE_STM32WLx
+
+#define LED_PIN PA0 // Green LED
+#define LED_STATE_ON 1
+
+#endif