Our previous flow was to perform a hijack before passing a
connection into Libpod, and then Libpod would attach to the
container's attach socket and begin forwarding traffic.
A problem emerges: we write the attach header as soon as the
attach complete. As soon as we write the header, the client
assumes that all is ready, and sends a Start request. This Start
may be processed *before* we successfully finish attaching,
causing us to lose output.
The solution is to handle hijacking inside Libpod. Unfortunately,
this requires a downright extensive refactor of the Attach and
HTTP Exec StartAndAttach code. I think the result is an
improvement in some places (a lot more errors will be handled
with a proper HTTP error code, before the hijack occurs) but
other parts, like the relocation of printing container logs, are
just *bad*. Still, we need this fixed now to get CI back into
good shape...
Fixes#7195
Signed-off-by: Matthew Heon <matthew.heon@pm.me>