Remove uses of DepInfo.transitive_libs

[scentini]

This is a step further towards #1051.

With this change, rules_rust doesn't need DepInfo.transitive_libs anymore. The only place where this field was used was to pass the files it contains as inputs to rust compile actions. We use DepInfo.transitive_crate_outputs for that now. For non-rlib compile actions, which need non-crate inputs as well, we add those inputs to the additional_transitive_inputs variable.