the `io` module may need a refactor

[bitquence]

• the name t_io is too short to convey the fact that it is only related to pipelines, and is somewhat misleadingly named after its overarching module
• t_redir_list seems sort of messy, its single header carries a lot of primitives. it may fit better as a sub-module of a broader redirection module

[vincent-lafouasse]

agreed

[bitquence]

maybe we can move t_io into some kind of module internal to execute since it's only used for pipelines

[vincent-lafouasse]

fair