This removes all the calls to `unwrap()` in the codebase, which made me found a couple of places where it wasn't needed, and could be improved. I also noticed we don't have dependabot updates for the test262 submodule and the interner dependencies, so I added those.
I added lints so that no new unwraps are added.
* Adds `cargo` dependabot checks for dependencies
- Allows dependabot to automatically check for dependency version
updates daily using cargo.
- `versioning-strategy` supports default strategy and lockfile-only for
cargo, will need to see which is more suitable.
- Perhaps add `rebase-strategy` and `reviewers` if necessary, although
with proper unit tests, shouldn't be too necessary.
* Adds github-actions updates to dependabot