Box ShellError in Value::Error (#8375)

# Description

Our `ShellError` at the moment has a `std::mem::size_of<ShellError>` of
136 bytes (on AMD64). As a result `Value` directly storing the struct
also required 136 bytes (thanks to alignment requirements).

This change stores the `Value::Error` `ShellError` on the heap.

Pro:
- Value now needs just 80 bytes
- Should be 1 cacheline less (still at least 2 cachelines)

Con:
- More small heap allocations when dealing with `Value::Error`
  - More heap fragmentation
  - Potential for additional required memcopies

# Further code changes

Includes a small refactor of `try` due to a type mismatch in its large
match.

# User-Facing Changes

None for regular users.

Plugin authors may have to update their matches on `Value` if they use
`nu-protocol`

Needs benchmarking to see if there is a benefit in real world workloads.
**Update** small improvements in runtime for workloads with high volume
of values. Significant reduction in maximum resident set size, when many
values are held in memory.

# Tests + Formatting

crates/nu_plugin_formats/src/from/ics.rs

@@ -28,12 +28,12 @@ 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 {
-                error: ShellError::UnsupportedInput(
+                error: Box::new(ShellError::UnsupportedInput(
                     format!("input cannot be parsed as .ics ({e})"),
                     "value originates from here".into(),
                     head,
                     span,
-                ),
+                )),
             }),
         }
     }

crates/nu_plugin_formats/src/from/vcf.rs

@@ -24,12 +24,12 @@ 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 {
-            error: ShellError::UnsupportedInput(
+            error: Box::new(ShellError::UnsupportedInput(
                 format!("input cannot be parsed as .vcf ({e})"),
                 "value originates from here".into(),
                 head,
                 span,
-            ),
+            )),
         },
     });