Into binary changes (#3758)

* kind of works but not what we really want

* updated `into binary` and `first` to work better together

* attempt to fix wasm build problem

* attempt #2 to fix wasm stuff

crates/nu-protocol/src/value.rs

@@ -82,6 +82,11 @@ impl UntaggedValue {
         }
     }
 
+    /// Returns true if this value represents a binary
+    pub fn is_binary(&self) -> bool {
+        matches!(self, &UntaggedValue::Primitive(Primitive::Binary(_)))
+    }
+
     /// Returns true if this value represents boolean true
     pub fn is_true(&self) -> bool {
         matches!(self, UntaggedValue::Primitive(Primitive::Boolean(true)))
@@ -421,6 +426,14 @@ impl Value {
         }
     }
 
+    /// View a Primitive::Binary as a Vec<u8>, if possible
+    pub fn as_binary_vec(&self) -> Result<Vec<u8>, ShellError> {
+        match &self.value {
+            UntaggedValue::Primitive(Primitive::Binary(bin)) => Ok(bin.to_vec()),
+            _ => Err(ShellError::type_error("binary", self.spanned_type_name())),
+        }
+    }
+
     /// View into the borrowed string contents of a Value, if possible
     pub fn as_forgiving_string(&self) -> Result<&str, ShellError> {
         match &self.value {