Find with regex flag (#4649)

* split find functions

* find command with regex

* corrected message

* cargo fmt

crates/nu-protocol/src/value/mod.rs

@@ -171,6 +171,7 @@ impl Clone for Value {
 }
 
 impl Value {
+    /// Converts into string values that can be changed into string natively
     pub fn as_string(&self) -> Result<String, ShellError> {
         match self {
             Value::Int { val, .. } => Ok(val.to_string()),