[BUG] Forks should always be in the same family

[ethteck]

From @1superchip

https://decomp.me/scratch/8LjDb
https://decomp.me/scratch/1SPeq

my scratch is a fork of KooShnoo's scratch but isn't in the family due to a different diff label

I'd expect them to be in the same family if one is a fork

[mkst]

Could we create a family_id field which is some guid that's always propagated on forks (and then use this to augment the list of scratches that also have the same target asm / target object+diff label) ?