rewrite linux fbcon and vgacon in Rust

[Artoria2e5]

Conversation in @AOSC-Dev telegram channel, translated:

@icenowy: (patching soft scrollback back to linux 5.9 fbcon because retro) Actually the most genius part of fbcon isn't the scrollback, it's the rotation They duplicated the same code three times for non-native rotation Thing needs a rewrite

@artoria2e5: in rust, right now, no_std

@Icenowy: but rust does not support every arch linux supports…

@szclsya: let's wait for gccrust…

@lionnatsu: we can just propose a safe keyword to the C++ committee