Add XIAO Wio-SX1262 overlay; support SX12xx bandwidths (including 62.5 kHz) as default

- boards/seeed/xiao_wio_sx1262: add overlay, .conf, board.yml
- app: support full set of SX12xx bandwidths; default BW set to 62 (62.5 kHz)
- Update Kconfig and prj.conf
- Update lora_modem.h/c for validation and mapping

build/zephyr/include/generated/xtensa_vectors.ld

@@ -0,0 +1,34 @@
+/* Automatically Generated Code - Do Not Edit */
+/* See arch/xtensa/core/gen_vector.py */
+
+  .z_xtensa_vectors : ALIGN(1024) {
+    z_xtensa_vecbase = .;
+    KEEP(*(.WindowVectors.text));
+    KEEP(*(.Level2InterruptVector.literal));
+    . = 0x180;
+    KEEP(*(.Level2InterruptVector.text));
+    KEEP(*(.Level3InterruptVector.literal));
+    . = 0x1c0;
+    KEEP(*(.Level3InterruptVector.text));
+    KEEP(*(.Level4InterruptVector.literal));
+    . = 0x200;
+    KEEP(*(.Level4InterruptVector.text));
+    KEEP(*(.Level5InterruptVector.literal));
+    . = 0x240;
+    KEEP(*(.Level5InterruptVector.text));
+    KEEP(*(.DebugExceptionVector.literal));
+    . = 0x280;
+    KEEP(*(.DebugExceptionVector.text));
+    KEEP(*(.NMIExceptionVector.literal));
+    . = 0x2c0;
+    KEEP(*(.NMIExceptionVector.text));
+    KEEP(*(.KernelExceptionVector.literal));
+    . = 0x300;
+    KEEP(*(.KernelExceptionVector.text));
+    KEEP(*(.UserExceptionVector.literal));
+    . = 0x340;
+    KEEP(*(.UserExceptionVector.text));
+    KEEP(*(.DoubleExceptionVector.literal));
+    . = 0x3c0;
+    KEEP(*(.DoubleExceptionVector.text));
+  }