Add bond conversion API between v1 and v2 bond data preserving old bonds

examples/NimBLE_Bond_Migration/NimBLE_Bond_Migration.ino

@@ -0,0 +1,60 @@
+/**
+ * NimBLE_Bond_Migration Demo:
+ *
+ * This example demonstrates running one-time bond-store migration before
+ * NimBLE initialization. Set NIMBLE_BOND_MIGRATION_MODE to select direction:
+ * 0 = off, 1 = migrate to current, 2 = migrate to v1.
+ */
+
+#include <Arduino.h>
+#include <NimBLEDevice.h>
+#include <NimBLEBondMigration.h>
+
+#ifndef NIMBLE_BOND_MIGRATION_MODE
+#define NIMBLE_BOND_MIGRATION_MODE 1
+#endif
+
+#if (NIMBLE_BOND_MIGRATION_MODE < 0) || (NIMBLE_BOND_MIGRATION_MODE > 2)
+#error "NIMBLE_BOND_MIGRATION_MODE must be 0 (off), 1 (to current), or 2 (to v1)"
+#endif
+
+void setup() {
+    using namespace NimBLEBondMigration;
+
+    Serial.begin(115200);
+    Serial.println("Starting NimBLE_Bond_Migration Demo");
+
+    bool success = false;
+#if NIMBLE_BOND_MIGRATION_MODE == 1
+    success = migrateBondStoreToCurrent();
+    Serial.printf("NimBLE_Bond_Migration to current %s\n", success ? "success" : "failed");
+#elif NIMBLE_BOND_MIGRATION_MODE == 2
+    success = migrateBondStoreToV1();
+    Serial.printf("NimBLE_Bond_Migration to v1 %s\n", success ? "success" : "failed");
+#endif
+
+    if (success) {
+        Serial.println("NimBLE_Bond_Migration completed, upload target firmware to continue");
+        while (true) {
+            delay(1000);
+        }
+    }
+
+    NimBLEDevice::init("NimBLE");
+    NimBLEDevice::setSecurityAuth(true, true, false); /** bonding, MITM, don't need BLE secure connections as we are using passkey pairing */
+    NimBLEDevice::setSecurityPasskey(123456);
+    NimBLEDevice::setSecurityIOCap(BLE_HS_IO_DISPLAY_ONLY); /** Display only passkey */
+    NimBLEServer*         pServer                  = NimBLEDevice::createServer();
+    NimBLEService*        pService                 = pServer->createService("ABCD");
+    NimBLECharacteristic* pSecureCharacteristic =
+        pService->createCharacteristic("1235",
+                                       NIMBLE_PROPERTY::READ | NIMBLE_PROPERTY::READ_ENC | NIMBLE_PROPERTY::READ_AUTHEN);
+
+    pSecureCharacteristic->setValue("Hello Secure BLE");
+
+    NimBLEAdvertising* pAdvertising = NimBLEDevice::getAdvertising();
+    pAdvertising->addServiceUUID("ABCD");
+    pAdvertising->start();
+}
+
+void loop() {}