Merge branch '2023-04-27-introduce-nvm-xip-block-storage-emulation'

Merge branch '2023-04-27-introduce-nvm-xip-block-storage-emulation'

To quote the author:
Adding block storage emulation for NVM XIP flash devices.

Some paltforms such as Corstone-1000 need to see NVM XIP raw flash
as a block storage device with read only capability.

Here NVM flash devices are devices with addressable
memory (e.g: QSPI NOR flash).

The NVM XIP block storage emulation provides the following features:

- Emulate NVM XIP raw flash as a block storage device with read only capability
- Being generic by design and can be used by any platform
- Device tree node
- Platforms can use multiple NVM XIP devices at the same time by defining a
  DT node for each one of them
- A generic NVMXIP block driver allowing to read from the XIP flash
- A generic NVMXIP Uclass driver for binding the block device
- A generic NVMXIP QSPI driver
- Implemented on top of memory-mapped IO (using readq macro)
- Enabling NVMXIP in sandbox64
- A sandbox test case
- Enabling NVMXIP in Corstone1000 platform as a use case

For more details please refer to doc/develop/driver-model/nvmxip.rst