[FEATURE] Save floppy disc changes on shutdown

[RichardBrown384]

Is your feature request related to a problem? Please describe.
It would be nice if the changes made to floppy discs would persist across sessions.

Describe the solution you'd like
When I shut down the emulator the files I wrote to the floppy disc stay written and are there when I restart the emulator.

Describe alternatives you've considered
None

Additional context
The WDC1722 already supports writing to disc (which is held in RAM during the application's run time). The feature
while tested is considered experimental and not currently enabled in order to protect user data in case of malfunction.