grep-cli: support files compressed by compress(1)

While Linux distributions (at least Arch Linux, RHEL, Debian) do not support
compressing files with compress(1), macOS & AIX do (the utility is part of
POSIX). Additionally, gzip is able to uncompress such compressed files and
provides an `uncompress` binary.

Closes #1547

crates/ignore/src/default_types.rs

@@ -234,6 +234,7 @@ pub const DEFAULT_TYPES: &[(&str, &[&str])] = &[
     ("xz", &["*.xz", "*.txz"]),
     ("yacc", &["*.y"]),
     ("yaml", &["*.yaml", "*.yml"]),
+    ("z", &["*.Z"]),
     ("zig", &["*.zig"]),
     ("zsh", &[
         ".zshenv", "zshenv",