Marc Khouri would like Owners Override to review this change.
[rust] Format imports using rustfmt
Set `imports_granularity = "Module"` in our rustfmt config, and format
all files using `fx format-code --all -- "*.rs"`.
This change allows for a consistent style across our codebase, and
provides format-on-save functionality for imports. The "Module" option
has a good balance of verbosity vs resistance to merge conflicts.
See the linked bug for additional rationale on this option.