Extra cargo options not passed to cargo metadata

[apoelstra]

🐛 Bug description

The build documentation suggests that you can pass extra flags to cargo build. The example given is --offline. A natural inference for a user is that --locked should work too.

In fact, neither are passed to cargo metadata, making neither --locked nor --offline behave the way they would if the user were calling cargo build --locked.

🤔 Expected Behavior

When calling wasm-pack build -- --locked, wasm-pack should not manipulate lockfiles at all, just like cargo build --locked. I believe all that is needed is to feed the extra cargo options into the cargo_metadata::MetadataCommand constructor alongside the manifest path. This is done in CrateData::new in manifest/mod.rs.

👟 Steps to reproduce

1. Delete your Cargo.lock.
2. Run `wasm-pack build -- --locked
3. Check whether the command succeeded and created a Cargo.lock file.

🌍 Your environment

Include the relevant details of your environment.
wasm-pack version: 0.10.3
rustc version: 1.71

[TakodaS]

Even --offline isn't passed to cargo build: #821
This feature is critical if you want to use wasm-pack in a nix derivation as they are isolated on purpose.

EDIT: I take this back. The problem is that wasm-pack build runs both cargo build, which is now passed extra parameters, and cargo install that you have no control over.