Sinicized culture decisions

[CarbonY26]

(self-assigned)

Since 1.33, when Yuan was formed, the culture would become Sino-Altaic. Of course, when Yuan was converted from CK2, it doesn't have that culture. A decision should be made to replicate what happens in vanilla EU4, which when enacted simply changes the primary culture to Sino-Altaic.

This could be extended to other dynasties like Jin (金) and Liao.