We've replaced the previous "--feature=" format with a single parameter
"--" which marks the start of the "cargo install" arguments, so now we
can use "-- --features foo", "-- --locked", etc.
Fixes#3162
Now the rust hooks can use the parameter `additional_dependencies` to
receive build-time features for the crate.
The features must start with the string "--feature=" following the name
of the feature; e.g. "--feature=full".
Fixes#3230
