Remote(tramp) rustfmt does not consider rustfmt.toml

[ileixe]

Currently, rust-format-buffer does not care about remote rustfmt.toml if user uses tramp. (Local works fine considering config file). Can we fix it should see the remote config file?

FYI: eglot-format-buffer works well for remote file, so for those who cares this issue, use the function instead.

[psibi]

I don't use tramp, but I would be happy to accept a PR with a test for the same.