uucore: Move pgrep/process.rs to uucore (#6483)

needed for https://github.com/uutils/procps/

Author: Krysztal112233

src/uucore/Cargo.toml

@@ -88,6 +88,7 @@ mode = ["libc"]
 perms = ["libc", "walkdir"]
 pipes = []
 process = ["libc"]
+proc-info = ["walkdir"]
 quoting-style = []
 ranges = []
 ringbuffer = []

src/uucore/src/lib/features.rs

@@ -45,6 +45,8 @@ pub mod entries;
 pub mod perms;
 #[cfg(all(unix, feature = "pipes"))]
 pub mod pipes;
+#[cfg(all(target_os = "linux", feature = "proc-info"))]
+pub mod proc_info;
 #[cfg(all(unix, feature = "process"))]
 pub mod process;