Test compiling & testing individual utilities

[tertsdiepraam]

The current CI only compiles all utilities at the same time, which works fine most of the time, but there are slight issues.

• crates.io requires individual compilation of each util. For 0.0.16, I ran into an issue where chroot was using the fs feature of uucore, but didn't declare it. This succeeded in the CI, because the fs feature was enabled by another util.
• There are tests which require multiple utils. These usually have #[cfg(feature = "util")] but not always and we should test for that. This also makes it more consistent to use cargo run --no-default-features --features util.

[cakebaker]

Fixed in #6212