implement possibility to store remanent data by firmware itself

All firmware files provided shall be able to store remanent data if this is configured in taglist.

• The remanent data shall be stored as a file in SYSVOLUME for all firmware except cifX. All firmwares except cifX shall not care for type of SYSVOLUME (so if it is a RAM disk the data will not be stored remanent).
• The file is created by the firmware as soon as the firmware starts if the file is non-existent. This helps to avoid filessystem corruption issues at runtime.
• The file shall be named "pnmrem.dat".
• The file shall contain complete remanent data generated by protocol stack plus additional reserve for future use. Expected file size 8 KB.
• When writing, the file shall be opened with attribute MID_FAT_FILEACCESS_NOFILETIME to avoid updating FAT each time.

For cifX firmware (and only for this firmware), a differentiation is needed depending on the type of SYSVOLUME.

• In case of flash filesystem, a file shall be used there, similar to all other firmwares.
• In case of RAM disc filesystem, the remanent data shall be stored directly in the serial flash of cifX card (similar to PNSV4).
  • flash offset 0x1B000 shall be used to avoid collision with remanent data stored by PNS