Auto merge of #72705 - Lucretiel:stdio-forwarding, r=Amanieu
Auto merge of #72705 - Lucretiel:stdio-forwarding, r=Amanieu

Added io forwarding methods to the stdio structs

Added methods to forward the `io::Read` and `io::Write` methods of the myriad wrapper structs in `stdio.rs` to their underlying readers / writers. This is especially important for the structs on the outside of a locking boundary, to ensure that the lock isn't being dropped and re-acquired in a loop.

graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust