Make the FrameBufferWriter and logger in to a separate crate so it can be reused by a kernel for quick start?

[duggaraju]

Right now the bootloader-x86_64-common crate has std dependencies. and doesn't compile with no_std flag. If that can be made to work with no_std or move the framebuffer logic to a separate crate it would be usable by kernel code and helps with quick start of a kernel that can log messages.

[zjijz]

bootloader-x86_64-common can (now) be compiled with no_std (https://github.com/rust-osdev/bootloader/blob/7c8e2ca63449f92cd1f7494b9cdc9fcf58b7375d/common/src/lib.rs#L1) and it did work in my custom kernel.