Let's officially have a way to pass the features used to build
cloud-hypervisor to the dev_cli.sh script.
This doesn't invalidate the previous commit, as we still don't what the
features_build variable to be quoted, otherwise we face the following
issue:
```
error: Found argument '--features tdx' which wasn't expected, or isn't valid in this context
Did you mean --features?
USAGE:
cargo build --all --features <FEATURES>...
```
Signed-off-by: Fabiano Fidêncio <fabiano.fidencio@intel.com>