This provides a trimmed-down version of //tvix, that allows building
tvix without all of the monorepo cloned.
We need to manually vendor in our patch for evans and ``--bytes-as-
base64`, as we don't have our depot overlays available in the josh
workspace.
Fixes https://b.tvl.fyi/issues/247.
Change-Id: I24306b8bb16ebf0df238b8f1eee0d47655a14827
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8000
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
