Convert more ShellError variants to named fields (#11222)

# Description

Convert errors to named fields:
* NeedsPositiveValue
* MissingConfigValue
* UnsupportedConfigValue
* DowncastNotPossible
* NonUtf8Custom
* NonUtf8
* DidYouMeanCustom
* DidYouMean
* ReadingFile
* RemoveNotPossible
* ChangedModifiedTimeNotPossible
* ChangedAccessTimeNotPossible

Part of #10700

crates/nu-cli/src/eval_file.rs

@@ -47,13 +47,13 @@ pub fn evaluate_file(
         let working_set = StateWorkingSet::new(engine_state);
         report_error(
             &working_set,
-            &ShellError::NonUtf8Custom(
-                format!(
+            &ShellError::NonUtf8Custom {
+                msg: format!(
                     "Input file name '{}' is not valid UTF8",
                     file_path.to_string_lossy()
                 ),
-                Span::unknown(),
-            ),
+                span: Span::unknown(),
+            },
         );
         std::process::exit(1);
     });