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-command/src/viewers/explore.rs

@@ -98,7 +98,9 @@ impl Command for Explore {
             Ok(Some(value)) => Ok(PipelineData::Value(value, None)),
             Ok(None) => Ok(PipelineData::Value(Value::default(), None)),
             Err(err) => Ok(PipelineData::Value(
-                Value::Error { error: err.into() },
+                Value::Error {
+                    error: Box::new(err.into()),
+                },
                 None,
             )),
         }

crates/nu-command/src/viewers/table.rs

@@ -305,7 +305,7 @@ fn handle_table_command(
         PipelineData::Value(Value::Error { error }, ..) => {
             // Propagate this error outward, so that it goes to stderr
             // instead of stdout.
-            Err(error)
+            Err(*error)
         }
         PipelineData::Value(Value::CustomValue { val, span }, ..) => {
             let base_pipeline = val.to_base_value(span)?.into_pipeline_data();
@@ -904,7 +904,7 @@ fn convert_to_table(
         }
 
         if let Value::Error { error } = item {
-            return Err(error.clone());
+            return Err(*error.clone());
         }
 
         let mut row = vec![];
@@ -1043,7 +1043,7 @@ fn convert_to_table2<'a>(
             }
 
             if let Value::Error { error } = item {
-                return Err(error.clone());
+                return Err(*error.clone());
             }
 
             let index = row + row_offset;
@@ -1085,7 +1085,7 @@ fn convert_to_table2<'a>(
             }
 
             if let Value::Error { error } = item {
-                return Err(error.clone());
+                return Err(*error.clone());
             }
 
             let mut value = convert_to_table2_entry(
@@ -1184,7 +1184,7 @@ fn convert_to_table2<'a>(
             }
 
             if let Value::Error { error } = item {
-                return Err(error.clone());
+                return Err(*error.clone());
             }
 
             let mut value = create_table2_entry(