Add --no-newline option to nu (#12410)

# Description
I have `nu` set as my shell in my editor, which allows me to easily pipe
selections of text to things like `str pascal-case` or even more complex
string operation pipelines, which I find super handy. However, the only
annoying thing is that I pretty much always have to add `| print -n` at
the end, because `nu` adds a newline when it prints the resulting value.

This adds a `--no-newline` option to stop that from happening, and then
you don't need to pipe to `print -n` anymore, you can just have your
shell command for your editor contain that flag.

# User-Facing Changes
- Add `--no-newline` command line option

# Tests + Formatting
- 🟢 `toolkit fmt`
- 🟢 `toolkit clippy`
- 🟢 `toolkit test`
- 🟢 `toolkit test stdlib`

tests/shell/mod.rs

@@ -273,6 +273,17 @@ fn run_in_noninteractive_mode() {
     assert!(child_output.stderr.is_empty());
 }
 
+#[test]
+fn run_with_no_newline() {
+    let child_output = std::process::Command::new(nu_test_support::fs::executable_path())
+        .args(["--no-newline", "-c", "\"hello world\""])
+        .output()
+        .expect("failed to run nu");
+
+    assert_eq!("hello world", String::from_utf8_lossy(&child_output.stdout)); // with no newline
+    assert!(child_output.stderr.is_empty());
+}
+
 #[test]
 fn main_script_can_have_subcommands1() {
     Playground::setup("main_subcommands", |dirs, sandbox| {