Port nRF54L15 to the s145 SoftDevice Arduino core (#11842)

* Remove the Zephyr based nRF54L15 port

* Add nRF54L15 port on the s145 Arduino core: nrf54l15dk and xiao_nrf54l15 variants

* nRF54L: errno-style nrfx results, flush console before assert reset

* nRF54L: log the SoftDevice status on Bluefruit failure, ignore the seed request event

* Support the Wio-LR2021 LoRa Plus expansion board with OLED and K1 on the XIAO nRF54L15 variant

* Consume the nRF54L15 platform, core and bootloader from their repositories

* Pin the nRF54L15 platform to v0.2.0

* nRF52: forward SoftDevice flash events taken by the main loop to the flash driver, log the pairing failure status

* Pin the nRF54L15 platform to v0.2.1

* Pin the nRF54L15 platform to v0.3.0

* Split the XIAO nRF54L15 variant into SX1262 and LoRa Plus environments, seed the SoftDevice on request, add the nrf54l15 CI build script

* Pin the nRF54L15 platform to meshtastic/platform-nordicnrf54 v0.3.1

* NRF54: Fix mtjson generation

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Co-authored-by: vidplace7 <vidplace7@gmail.com>

src/FSCommon.cpp

@@ -40,7 +40,11 @@ size_t fsUsedBytes()
         return 0;
     size_t blocks = 0;
     FSCom._lockFS();
+#if LFS_VERSION_MAJOR >= 2
+    int err = lfs_fs_traverse(fs, fsCountBlockCb, &blocks);
+#else
     int err = lfs_traverse(fs, fsCountBlockCb, &blocks);
+#endif
     FSCom._unlockFS();
     if (err < 0)
         return fsTotalBytes(); // report "full" so capacity checks fail safe