testing: Add split BLE tests (#2737)

* Enhance the BLE test runner to build additional peripheral builds
  when detecting peripheral*.overlay files in the test.
* Add basic and multiple-peripheral tests to exercise the testing
  support
* Add test for triggering local behaviors on split peripherals.

fix(ble): Fix building split code w/o settings

* Properly exclude storing peripheral addresses to settings when
  settings support isn't turned on.

app/src/ble.c

@@ -379,10 +379,11 @@ int zmk_ble_put_peripheral_addr(const bt_addr_le_t *addr) {
             LOG_DBG("Storing peripheral %s in slot %d", addr_str, i);
             bt_addr_le_copy(&peripheral_addrs[i], addr);
 
+#if IS_ENABLED(CONFIG_SETTINGS)
             char setting_name[32];
             sprintf(setting_name, "ble/peripheral_addresses/%d", i);
             settings_save_one(setting_name, addr, sizeof(bt_addr_le_t));
-
+#endif // IS_ENABLED(CONFIG_SETTINGS)
             return i;
         }
     }