Stability tracking - Rustfmt

Add to Rust product:

[x] Add to Rust repo
[ ] agree on stability criteria
[x] tests running and passing on CI
[x] overwrite mode by default
[ ] implement stable/unstable command line arguments (unstable options are now supported, but we need to decide which options should be stable)
[ ] resolve 'warnings for skipped sections'

rust-dev-tools / dev-tools-team