Add simple stdin input command (#754)

* Add simple stdin input command

* Add binary input

* Tweak binary view

crates/nu-command/src/default_context.rs

@@ -166,6 +166,7 @@ pub fn create_default_context(cwd: impl AsRef<Path>) -> EngineState {
             AnsiGradient,
             AnsiStrip,
             Clear,
+            Input,
             Kill,
             Sleep,
         };