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-plugin/src/protocol/mod.rs

@@ -78,7 +78,7 @@ impl From<ShellError> for LabeledError {
                 msg: format!("can't convert from {input} to {expected}"),
                 span: Some(span),
             },
-            ShellError::DidYouMean(suggestion, span) => LabeledError {
+            ShellError::DidYouMean { suggestion, span } => LabeledError {
                 label: "Name not found".into(),
                 msg: format!("did you mean '{suggestion}'?"),
                 span: Some(span),