Escape path that could be a flag (#10721)

# Description
Files that begin with dashes can be ambiguous when passed to commands
like `ls`. For example if there exists a file `--help`, it might be
considered a flag if not properly escaped. This PR escapes any file that
begins with a dash.

# User-Facing Changes

Files beginning with dashes will be escaped.

# Tests + Formatting

Tests are added.

crates/nu-cli/src/completions/completion_common.rs

@@ -152,7 +152,9 @@ pub fn complete_item(
 pub fn escape_path(path: String, dir: bool) -> String {
     let filename_contaminated = !dir && path.contains(['\'', '"', ' ', '#', '(', ')']);
     let dirname_contaminated = dir && path.contains(['\'', '"', ' ', '#']);
-    if filename_contaminated || dirname_contaminated || path.parse::<f64>().is_ok() {
+    let maybe_flag = path.starts_with('-');
+    let maybe_number = path.parse::<f64>().is_ok();
+    if filename_contaminated || dirname_contaminated || maybe_flag || maybe_number {
         format!("`{path}`")
     } else {
         path

crates/nu-cli/tests/completions.rs

@@ -527,6 +527,10 @@ fn file_completion_quoted() {
     let suggestions = completer.complete(target_dir, target_dir.len());
 
     let expected_paths: Vec<String> = vec![
+        "`--help`".to_string(),
+        "`-42`".to_string(),
+        "`-inf`".to_string(),
+        "`4.2`".to_string(),
         "`te st.txt`".to_string(),
         "`te#st.txt`".to_string(),
         "`te'st.txt`".to_string(),