.hdm floppy format is really mixed 5.25" / 3.5"

[angelosa]

This is mostly an hash files problem. .hdm is mostly used by Japanese computers, most notably pc98 but also fmtowns, mz2500 and x68k. Reading them aren't really form factor dependant, both floppy_5_25 and floppy_3_5 can mostly read them (exception being if they explicitly uses the 1.44mb AT mode in pc98, which there aren't that many currently hooked up anyway).

Case to point: generic_flop_525:akazucc, that is also FM Towns compatible too but that never got a 5.25" option.

Needs some way to define an alias for interface="floppy_dont_care_about_form_factor" so that SW lists can successfully mount them without silly entry duplication.