Moves builder/shell_parser and into its own subpackage at builder/shell since it
has no dependencies other than the standard library. This will make it
much easier to vendor for downstream libraries, without pulling all the
dependencies of builder/.
Fixes#36154
Signed-off-by: Matt Rickard <mrick@google.com>
rewritten from github.com/moby/moby a634526d14639c6b98c509a069ef29e2b69c0ef0
Yuichiro Kaneko
Tonis Tiigi
Daniel Nephin
Matt Rickard