Rollup merge of #82507 - jyn514:tidy-windows, r=Mark-Simulacrum

Rollup merge of #82507 - jyn514:tidy-windows, r=Mark-Simulacrum

Rename the `tidy` binary to `rust-tidy`

This avoids naming collisions, particularly on Windows where the
dynamic library variable is PATH and setting it causes the in-tree
`tidy` to take precedence over the HTML tidy used by compiletest.

This doesn't change the x.py interface in any way, it still accepts `x.py test tidy` and prints error messages about `tidy`. It only changes the name of the file on disk.

Fixes https://github.com/rust-lang/rust/issues/82501.