Remove dfr from dataframe commands (#5760)

* input and output tests

* input and output types for dfr

* expression converter

* remove deprecated command

* correct expressions

* cargo clippy

* identifier for ls

* cargo clippy

* type for head and tail expression

* modify full cell path if block

crates/nu-cli/src/menus/help_completions.rs

@@ -87,7 +87,7 @@ impl NuHelpCompleter {
 
                 let extra: Vec<String> = examples
                     .iter()
-                    .map(|example| example.example.to_string())
+                    .map(|example| example.example.replace('\n', "\r\n"))
                     .collect();
 
                 Suggestion {