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-cmd-dataframe/src/dataframe/values/nu_dataframe/mod.rs

@@ -288,7 +288,10 @@ impl NuDataFrame {
                 .collect::<Vec<String>>();
 
             let option = did_you_mean(&possibilities, column).unwrap_or_else(|| column.to_string());
-            ShellError::DidYouMean(option, span)
+            ShellError::DidYouMean {
+                suggestion: option,
+                span,
+            }
         })?;
 
         let df = DataFrame::new(vec![s.clone()]).map_err(|e| {

crates/nu-cmd-dataframe/src/dataframe/values/nu_dataframe/operations.rs

@@ -24,10 +24,10 @@ impl NuDataFrame {
         match right {
             Value::CustomValue { val: rhs, .. } => {
                 let rhs = rhs.as_any().downcast_ref::<NuDataFrame>().ok_or_else(|| {
-                    ShellError::DowncastNotPossible(
-                        "Unable to create dataframe".to_string(),
-                        rhs_span,
-                    )
+                    ShellError::DowncastNotPossible {
+                        msg: "Unable to create dataframe".to_string(),
+                        span: rhs_span,
+                    }
                 })?;
 
                 match (self.is_series(), rhs.is_series()) {

crates/nu-cmd-dataframe/src/dataframe/values/nu_expression/custom_value.rs

@@ -57,7 +57,10 @@ fn compute_with_value(
     match right {
         Value::CustomValue { val: rhs, .. } => {
             let rhs = rhs.as_any().downcast_ref::<NuExpression>().ok_or_else(|| {
-                ShellError::DowncastNotPossible("Unable to create expression".to_string(), rhs_span)
+                ShellError::DowncastNotPossible {
+                    msg: "Unable to create expression".into(),
+                    span: rhs_span,
+                }
             })?;
 
             match rhs.as_ref() {