move fs.h to fs/fs.h and
create a shim for backward-compatibility.
No functional changes to the headers.
A warning in the shim can be controlled with CONFIG_COMPAT_INCLUDES.
Related to #16539
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
Adds required Kconfig options for flash driver.
Adds FatFS filesystem for flash disk.
Fixes#14459.
Note: As USB MSC does not support multiple disks (see #14937),
only one (flash by default, modify CONFIG_MASS_STORAGE_DISK_NAME
to "RAM" for RAM disk) will appear to host.
Signed-off-by: Marcin Szymczyk <Marcin.Szymczyk@nordicsemi.no>
