Add a CI check to ensure Cargo.lock file remains up-to-date (#597)

* Add a CI check to ensure Cargo.lock file remains up-to-date

This adds a new CI "cargo-verification" check to ensure the `Cargo.lock`
file is valid for the current state of all manifests within the
workspace. This avoids having `Cargo.lock` files changes leak into
unrelated PRs, and allows tools like Nix to always have a valid lock
file present at each published release to ensure reproducible builds.

* Use default features, targets for lock file check

.github/workflows/ci.yml

@@ -94,6 +94,8 @@ jobs:
             args: --all-targets --all-features
           - command: make
             args: build
+          - command: check
+            args: --locked --workspace
           - command: test
             args: --all-targets --all-features --workspace --exclude fuel-p2p
           - command: test