Allow auto-cd on trailing slash (#10585)

# Description

This allows auto-cd (cd'ing by just typing the directory name with `cd`)
to work if there's a trailing slash in the path.

# User-Facing Changes

This should be an improvement over previous behaviour. I don't think
this clashes with any existing assumptions.

# Tests + Formatting
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crates/nu-cli/src/repl.rs

@@ -820,16 +820,29 @@ fn looks_like_path(orig: &str) -> bool {
         || orig.starts_with('~')
         || orig.starts_with('/')
         || orig.starts_with('\\')
+        || orig.ends_with(std::path::MAIN_SEPARATOR)
 }
 
+#[cfg(windows)]
 #[test]
 fn looks_like_path_windows_drive_path_works() {
-    let on_windows = cfg!(windows);
-    assert_eq!(looks_like_path("C:"), on_windows);
-    assert_eq!(looks_like_path("D:\\"), on_windows);
-    assert_eq!(looks_like_path("E:/"), on_windows);
-    assert_eq!(looks_like_path("F:\\some_dir"), on_windows);
-    assert_eq!(looks_like_path("G:/some_dir"), on_windows);
+    assert!(looks_like_path("C:"));
+    assert!(looks_like_path("D:\\"));
+    assert!(looks_like_path("E:/"));
+    assert!(looks_like_path("F:\\some_dir"));
+    assert!(looks_like_path("G:/some_dir"));
+}
+
+#[cfg(windows)]
+#[test]
+fn trailing_slash_looks_like_path() {
+    assert!(looks_like_path("foo\\"))
+}
+
+#[cfg(not(windows))]
+#[test]
+fn trailing_slash_looks_like_path() {
+    assert!(looks_like_path("foo/"))
 }
 
 #[test]