support features

[Emilgardis]

Tests are not shown if they are behind a #[cfg(feature = "my_feature)]", this extension should support forwarding features to all cargo commands. i.e cargo test --features "a b c" -- --list

One thing to note is that you can not use --features in cargo workspaces

[calebcartwright]

Thanks for reach out @Emilgardis! I had a similar realization the other week but hadn't gotten around to writing anything up yet.

I wasn't sure whether just including --all-features by default would suffice or if we'd need something more complex like user configured values and/or trying to do some auto detection based on the metadata output

[Emilgardis]

I think --all-features is fine if you can specify it with a config key, as sometimes using --all-features can cause issues, even though features should be additive.