This change adds an opt-in feature for creating .so symlinks to
all injected driver files in a contianer.
If features.dot-so-symlinks = true is set in the config.toml, the creation
of symlinks for driver files is enabled. This can also be triggered on a
per-container basis using the envvar NVIDIA_DOT_SO_SYMLINKS=enabled.
Signed-off-by: Evan Lezar <elezar@nvidia.com>