Remove unused dependencies (#6945)

* Remove unused dependencies

Inspired by #6938 ran `cargo +nightly udeps --features extra`.
Removes 2 crates and should remove an unnecessary intra-workspace
dependency which might open up further opportunities for compilation.

* Make windows-only dependency conditional in toml

`omnipath` is only used on Windows and already behind a `#[cfg]` block
in the code. Made the dependency in `Cargo.toml` conditional as well.

* Make `nu-pretty-hex` example a proper example

This allows making `rand` a dev-dependency in this crate.

crates/nu-pretty-hex/examples/demo.rs

@@ -0,0 +1,51 @@
+use nu_pretty_hex::*;
+
+fn main() {
+    let config = HexConfig {
+        title: true,
+        ascii: true,
+        width: 16,
+        group: 4,
+        chunk: 1,
+        address_offset: 0,
+        skip: Some(10),
+        // length: Some(5),
+        // length: None,
+        length: Some(50),
+    };
+
+    let my_string = "Darren Schroeder 😉";
+    println!("ConfigHex\n{}\n", config_hex(&my_string, config));
+    println!("SimpleHex\n{}\n", simple_hex(&my_string));
+    println!("PrettyHex\n{}\n", pretty_hex(&my_string));
+    println!("ConfigHex\n{}\n", config_hex(&my_string, config));
+
+    // let mut my_str = String::new();
+    // for x in 0..256 {
+    //     my_str.push(x as u8);
+    // }
+    let mut v: Vec<u8> = vec![];
+    for x in 0..=127 {
+        v.push(x);
+    }
+    let my_str = String::from_utf8_lossy(&v[..]);
+
+    println!("First128\n{}\n", pretty_hex(&my_str.as_bytes()));
+    println!(
+        "First128-Param\n{}\n",
+        config_hex(&my_str.as_bytes(), config)
+    );
+
+    let mut r_str = String::new();
+    for _ in 0..=127 {
+        r_str.push(rand::random::<u8>() as char);
+    }
+
+    println!("Random127\n{}\n", pretty_hex(&r_str));
+}
+
+//chunk 0 44617272656e20536368726f65646572   Darren Schroeder
+//chunk 1 44 61 72 72  65 6e 20 53  63 68 72 6f  65 64 65 72   Darren Schroeder
+//chunk 2 461 7272 656e 2053  6368 726f 6564 6572   Darren Schroeder
+//chunk 3 46172 72656e 205363 68726f  656465 72   Darren Schroeder
+//chunk 4 44617272 656e2053 6368726f 65646572   Darren Schroeder