Add --long flag for sys cpu (#14485)

# Description

Fixes #14470 where the `sys cpu` command is slow. This was done by
removing the `cpu_usage` column from the default output, since it takes
400ms to calculate. Instead a `--long` flag was added that, when
provided, adds back the `cpu_usage` column.

```nu
# Before
> bench { sys cpu | length } | get mean
401ms 591µs 896ns

# After
> bench { sys cpu | length } | get mean
500µs 13ns # around 1-2ms in practice
```

# User-Facing Changes

- `sys cpu` no longer has a `cpu_usage` column by default.
- Added  a `--long` flag for `sys cpu` to add back the removed column.

crates/nu-engine/src/command_prelude.rs

@@ -3,6 +3,6 @@ pub use nu_protocol::{
     ast::CellPath,
     engine::{Call, Command, EngineState, Stack, StateWorkingSet},
     record, ByteStream, ByteStreamType, Category, ErrSpan, Example, IntoInterruptiblePipelineData,
-    IntoPipelineData, IntoSpanned, PipelineData, Record, ShellError, Signature, Span, Spanned,
-    SyntaxShape, Type, Value,
+    IntoPipelineData, IntoSpanned, IntoValue, PipelineData, Record, ShellError, Signature, Span,
+    Spanned, SyntaxShape, Type, Value,
 };