undefined reference to `BlockDevice::get_default_instance()' and other problems with flash examples

Hi, I'm trying the various examples for the flash features of the Uno R4 but a recursive compilation error is as follows:

```text
undefined reference to `BlockDevice::get_default_instance()'
```

The problem is caused by the lack of the right tag for the architecture in the BlockDevice file.cpp :

https://github.com/arduino/ArduinoCore-renesas/blob/149f78b6490ccbafeb420f68919c381a5bdb6e21/libraries/BlockDevices/BlockDevice.cpp#L20

by correcting and putting adding the right platform macro for example `ARDUINO_UNOR4_MINIMA`, the problem moves to compiling and defining parts of the `QSPIFlashBlockDevice` library.

Is this a known problem? I can't use the flash features of the board.

I use the last core 1.0.1 for Arduino Uno R4.

Start with libraries/BlockDevices/BlockDevice.cpp at the linked reference and reproduce the failure using the Uno R4 flash examples with core 1.0.1. Trace the missing BlockDevice::get_default_instance() reference and then the reported QSPIFlashBlockDevice compilation and definition errors. Done means the flash examples compile successfully for the Uno R4.

Written by the indexing model from the issue text.