Convert Shellerror::GenericError to named fields (#11230)

# Description

Replace `.to_string()` used in `GenericError` with `.into()` as
`.into()` seems more popular

Replace `Vec::new()` used in `GenericError` with `vec![]` as `vec![]`
seems more popular

(There are so, so many)

crates/nu-command/src/filesystem/mktemp.rs

@@ -119,13 +119,13 @@ impl Command for Mktemp {
                     })?
             }
             Err(e) => {
-                return Err(ShellError::GenericError(
-                    format!("{}", e),
-                    format!("{}", e),
-                    None,
-                    None,
-                    Vec::new(),
-                ));
+                return Err(ShellError::GenericError {
+                    error: format!("{}", e),
+                    msg: format!("{}", e),
+                    span: None,
+                    help: None,
+                    inner: vec![],
+                });
             }
         };
         Ok(PipelineData::Value(Value::string(res, span), None))