Add support for new NRF52 board, MeshLink (#5736)

* Add support for MeshLink

* Updated, enabled watchdog and added button definition

* added eink variant and removed some compile errors

* Small board json file edit

* Finally got trunk working (somehow?), this is just cleanup with trunk fmt

* Various improvements and cleanup. Removed the use of PIN_3V3_En and defined a specific WD_EN pin instead for better clarity. Will do a bit more testing asap to make sure everything still works as intended :)

* Enable on-board QSPI Flash

* run trunk fmt with clang-format

---------

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>
Co-authored-by: Thomas Göttgens <tgoettgens@gmail.com>
Co-authored-by: Austin <vidplace7@gmail.com>

variants/meshlink/variant.cpp

@@ -0,0 +1,23 @@
+#include "variant.h"
+#include "nrf.h"
+#include "wiring_constants.h"
+#include "wiring_digital.h"
+
+const uint32_t g_ADigitalPinMap[] = {
+    // P0
+    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
+
+    // P1
+    32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47};
+
+void initVariant()
+{
+    pinMode(PIN_LED1, OUTPUT);
+    digitalWrite(PIN_LED1, HIGH); // turn off the white led while booting
+                                  // otherwise it will stay lit for several seconds (could be annoying)
+
+#ifdef PIN_WD_EN
+    pinMode(PIN_WD_EN, OUTPUT);
+    digitalWrite(PIN_WD_EN, HIGH); // Enable the Watchdog at boot
+#endif
+}