Convert ShellError::UnsupportedInput to named fields (#10971)

# Description

This is easy to do with rust-analyzer, but I didn't want to just pump
these all out without feedback.

Part of #10700

# User-Facing Changes

None

# Tests + Formatting

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

# After Submitting

N/A

---------

Co-authored-by: Stefan Holderbach <sholderbach@users.noreply.github.com>

crates/nu_plugin_formats/src/from/ics.rs

@@ -36,12 +36,12 @@ pub fn from_ics_call(call: &EvaluatedCall, input: &Value) -> Result<Value, Label
         match calendar {
             Ok(c) => output.push(calendar_to_value(c, head)),
             Err(e) => output.push(Value::error(
-                ShellError::UnsupportedInput(
-                    format!("input cannot be parsed as .ics ({e})"),
-                    "value originates from here".into(),
-                    head,
-                    span,
-                ),
+                ShellError::UnsupportedInput {
+                    msg: format!("input cannot be parsed as .ics ({e})"),
+                    input: "value originates from here".into(),
+                    msg_span: head,
+                    input_span: span,
+                },
                 span,
             )),
         }

crates/nu_plugin_formats/src/from/ini.rs

@@ -40,12 +40,12 @@ pub fn from_ini_call(call: &EvaluatedCall, input: &Value) -> Result<Value, Label
             // all sections with all its key value pairs
             Ok(Value::record(sections, span))
         }
-        Err(err) => Err(ShellError::UnsupportedInput(
-            format!("Could not load ini: {err}"),
-            "value originates from here".into(),
-            head,
-            span,
-        )
+        Err(err) => Err(ShellError::UnsupportedInput {
+            msg: format!("Could not load ini: {err}"),
+            input: "value originates from here".into(),
+            msg_span: head,
+            input_span: span,
+        }
         .into()),
     }
 }

crates/nu_plugin_formats/src/from/vcf.rs

@@ -32,12 +32,12 @@ pub fn from_vcf_call(call: &EvaluatedCall, input: &Value) -> Result<Value, Label
     let iter = parser.map(move |contact| match contact {
         Ok(c) => contact_to_value(c, head),
         Err(e) => Value::error(
-            ShellError::UnsupportedInput(
-                format!("input cannot be parsed as .vcf ({e})"),
-                "value originates from here".into(),
-                head,
-                span,
-            ),
+            ShellError::UnsupportedInput {
+                msg: format!("input cannot be parsed as .vcf ({e})"),
+                input: "value originates from here".into(),
+                msg_span: head,
+                input_span: span,
+            },
             span,
         ),
     });