To avoid code duplication with the users of OBuilder as a library
(think ocluster-worker).

Otherwise embedded text get crlf line endings.

Mounts are read-write to preserve current behaviour.

This allows to specify the entrypoint of a `Sandbox.run job`. This is
only needed for the Docker sandbox, to override the Docker image
entrypoint.

Granted, it's more difficult to read, but way easier to copy-paste to
inspect manually what's happening.

This prevents errors on Windows where a file cannot be renamed, moved
or deleted if it is open by another process. It also ensure that the
database is left in a clean state.

…q-cmdliner', 'MisterDA/docker-windows-spec' and 'MisterDA/docker-windows-prerequisites' into docker

Checking the result for the Docker backend requires asynchronous calls
to Docker.

With the Docker backend on Windows, it's easier to store logs in a
location where they're not moved, as a directory cannot be renamed if
it contains open file descriptors.

For the btrfs and zfs backends, the original location is retained.