feat: add fifo buffer

[So1aric]

Add fifo-open typed command, which open a fifo file. This buffer shouldn't be edit imo, so I disable all the edit operation, but you still can select and copy-paste from it, which is expected.

This allow us to view a command's output in a buffer. Maybe a new command sh-to-fifo which create a temporary fifo, pipe the output to it, fifo-open the fifo could be introduced.

[CalebLarsen]

I'm having a hard time understanding the use case of this feature.

What is being added that can't be done with regular open and the shell commands?

Is it live updating?

[So1aric]

I'm trying to add functions that pick the fifobuffers and commands that write to a fifo, which might enable sth. like a repl buffer