Convert FileNotFound to named fields (#11120)

# Description

Part of #10700

# User-Facing Changes

None

# Tests + Formatting

- 🟢 `toolkit fmt`
- 🟢 `toolkit clippy`
- 🟢 `toolkit test`
- 🟢 `toolkit test stdlib`

# After Submitting

N/A

crates/nu-command/src/env/source_env.rs

@@ -55,7 +55,9 @@ impl Command for SourceEnv {
         )? {
             PathBuf::from(&path)
         } else {
-            return Err(ShellError::FileNotFound(source_filename.span));
+            return Err(ShellError::FileNotFound {
+                span: source_filename.span,
+            });
         };
 
         if let Some(parent) = file_path.parent() {

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

@@ -111,7 +111,7 @@ impl Command for Cp {
         };
 
         if sources.is_empty() {
-            return Err(ShellError::FileNotFound(src.span));
+            return Err(ShellError::FileNotFound { span: src.span });
         }
 
         if sources.len() > 1 && !destination.is_dir() {

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

@@ -80,7 +80,9 @@ impl Command for Mv {
             arg_glob(&spanned_source, &path).map_or_else(|_| Vec::new(), Iterator::collect);
 
         if sources.is_empty() {
-            return Err(ShellError::FileNotFound(spanned_source.span));
+            return Err(ShellError::FileNotFound {
+                span: spanned_source.span,
+            });
         }
 
         // We have two possibilities.

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

@@ -105,7 +105,7 @@ impl Command for Open {
 
             for path in nu_engine::glob_from(&path, &cwd, call_span, None)
                 .map_err(|err| match err {
-                    ShellError::DirectoryNotFound(span, _) => ShellError::FileNotFound(span),
+                    ShellError::DirectoryNotFound(span, _) => ShellError::FileNotFound { span },
                     _ => err,
                 })?
                 .1

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

@@ -173,7 +173,7 @@ impl Command for UCp {
         for p in paths {
             let exp_files = arg_glob(&p, &cwd)?.collect::<Vec<GlobResult>>();
             if exp_files.is_empty() {
-                return Err(ShellError::FileNotFound(p.span));
+                return Err(ShellError::FileNotFound { span: p.span });
             };
             let mut app_vals: Vec<PathBuf> = Vec::new();
             for v in exp_files {

crates/nu-command/src/system/nu_check.rs

@@ -117,7 +117,9 @@ impl Command for NuCheck {
                             if let Some(path) = path {
                                 path
                             } else {
-                                return Err(ShellError::FileNotFound(path_str.span));
+                                return Err(ShellError::FileNotFound {
+                                    span: path_str.span,
+                                });
                             }
                         }
                         Err(error) => return Err(error),