[Rust] Including dependencies in the analysis

Hi, is there any way to include cargo dependencies within the generated dbs? Right now im generating it like this

```bash
codeql database create rust-db \
--language=rust \
--source-root . \
--command "cargo build --all-targets --all-features" \
--extractor-option rust.cargo_all_targets=true \
--extractor-option rust.extract_dependencies_as_source=true \
--overwrite
```

But my queries still dont seem to go down into my dependecies

Start by reproducing the listed `codeql database create` command with the Rust extractor options and checking whether queries traverse the generated database's dependencies. Done means Rust cargo dependencies are included in the database analysis as requested.

Written by the indexing model from the issue text.