Add rustfmt.toml to mantain format consistency

[yollotltam]

Thid PR adds rustfmt.toml, currently the following rules were added:

• fn_params_layout = "Tall" : https://rust-lang.github.io/rustfmt/?version=v1.6.0&search=#fn_params_layout
• edition = "2021" https://rust-lang.github.io/rustfmt/?version=v1.6.0&search=edition#edition
• match_block_trailing_comma = true https://rust-lang.github.io/rustfmt/?version=v1.6.0&search=#match_block_trailing_comma

There are some rules that may be convenient to run like:

• https://rust-lang.github.io/rustfmt/?version=v1.6.0&search=group#imports_granularity
• https://rust-lang.github.io/rustfmt/?version=v1.6.0&search=group#group_imports But they are unstable and can only be run with nightly.

I will run make fix when reviewers agree on the rules.

[calavera]

Those are fine by me. I usually add these because I like to keep imports ordered, but it requires running cargo fmt with nightly:

unstable_features = true
imports_granularity = "Crate"
reorder_imports = true

[yollotltam]

Those are fine by me. I usually add these because I like to keep imports ordered, but it requires running cargo fmt with nightly:

unstable_features = true
imports_granularity = "Crate"
reorder_imports = true

Yeah me too, I just update the PR comment with those rules.

[richarddavison]

LGTM but can we apply this format for all rs files in same PR? (check is failing)