Replace ExternalStream with new ByteStream type (#12774)

# Description
This PR introduces a `ByteStream` type which is a `Read`-able stream of
bytes. Internally, it has an enum over three different byte stream
sources:
```rust
pub enum ByteStreamSource {
    Read(Box<dyn Read + Send + 'static>),
    File(File),
    Child(ChildProcess),
}
```

This is in comparison to the current `RawStream` type, which is an
`Iterator<Item = Vec<u8>>` and has to allocate for each read chunk.

Currently, `PipelineData::ExternalStream` serves a weird dual role where
it is either external command output or a wrapper around `RawStream`.
`ByteStream` makes this distinction more clear (via `ByteStreamSource`)
and replaces `PipelineData::ExternalStream` in this PR:
```rust
pub enum PipelineData {
    Empty,
    Value(Value, Option<PipelineMetadata>),
    ListStream(ListStream, Option<PipelineMetadata>),
    ByteStream(ByteStream, Option<PipelineMetadata>),
}
```

The PR is relatively large, but a decent amount of it is just repetitive
changes.

This PR fixes #7017, fixes #10763, and fixes #12369.

This PR also improves performance when piping external commands. Nushell
should, in most cases, have competitive pipeline throughput compared to,
e.g., bash.
| Command | Before (MB/s) | After (MB/s) | Bash (MB/s) |
| -------------------------------------------------- | -------------:|
------------:| -----------:|
| `throughput \| rg 'x'` | 3059 | 3744 | 3739 |
| `throughput \| nu --testbin relay o> /dev/null` | 3508 | 8087 | 8136 |

# User-Facing Changes
- This is a breaking change for the plugin communication protocol,
because the `ExternalStreamInfo` was replaced with `ByteStreamInfo`.
Plugins now only have to deal with a single input stream, as opposed to
the previous three streams: stdout, stderr, and exit code.
- The output of `describe` has been changed for external/byte streams.
- Temporary breaking change: `bytes starts-with` no longer works with
byte streams. This is to keep the PR smaller, and `bytes ends-with`
already does not work on byte streams.
- If a process core dumped, then instead of having a `Value::Error` in
the `exit_code` column of the output returned from `complete`, it now is
a `Value::Int` with the negation of the signal number.

# After Submitting
- Update docs and book as necessary
- Release notes (e.g., plugin protocol changes)
- Adapt/convert commands to work with byte streams (high priority is
`str length`, `bytes starts-with`, and maybe `bytes ends-with`).
- Refactor the `tee` code, Devyn has already done some work on this.

---------

Co-authored-by: Devyn Cairns <devyn.cairns@gmail.com>

crates/nu-protocol/src/errors/shell_error.rs

@@ -1,5 +1,6 @@
 use miette::Diagnostic;
 use serde::{Deserialize, Serialize};
+use std::io;
 use thiserror::Error;
 
 use crate::{
@@ -1374,42 +1375,79 @@ impl ShellError {
     }
 }
 
-impl From<std::io::Error> for ShellError {
-    fn from(input: std::io::Error) -> ShellError {
-        ShellError::IOError {
-            msg: format!("{input:?}"),
+impl From<io::Error> for ShellError {
+    fn from(error: io::Error) -> ShellError {
+        if error.kind() == io::ErrorKind::Other {
+            match error.into_inner() {
+                Some(err) => match err.downcast() {
+                    Ok(err) => *err,
+                    Err(err) => Self::IOError {
+                        msg: err.to_string(),
+                    },
+                },
+                None => Self::IOError {
+                    msg: "unknown error".into(),
+                },
+            }
+        } else {
+            Self::IOError {
+                msg: error.to_string(),
+            }
         }
     }
 }
 
-impl From<Spanned<std::io::Error>> for ShellError {
-    fn from(error: Spanned<std::io::Error>) -> Self {
-        ShellError::IOErrorSpanned {
-            msg: error.item.to_string(),
-            span: error.span,
+impl From<Spanned<io::Error>> for ShellError {
+    fn from(error: Spanned<io::Error>) -> Self {
+        let Spanned { item: error, span } = error;
+        if error.kind() == io::ErrorKind::Other {
+            match error.into_inner() {
+                Some(err) => match err.downcast() {
+                    Ok(err) => *err,
+                    Err(err) => Self::IOErrorSpanned {
+                        msg: err.to_string(),
+                        span,
+                    },
+                },
+                None => Self::IOErrorSpanned {
+                    msg: "unknown error".into(),
+                    span,
+                },
+            }
+        } else {
+            Self::IOErrorSpanned {
+                msg: error.to_string(),
+                span,
+            }
         }
     }
 }
 
-impl std::convert::From<Box<dyn std::error::Error>> for ShellError {
-    fn from(input: Box<dyn std::error::Error>) -> ShellError {
+impl From<ShellError> for io::Error {
+    fn from(error: ShellError) -> Self {
+        io::Error::new(io::ErrorKind::Other, error)
+    }
+}
+
+impl From<Box<dyn std::error::Error>> for ShellError {
+    fn from(error: Box<dyn std::error::Error>) -> ShellError {
         ShellError::IOError {
-            msg: input.to_string(),
+            msg: error.to_string(),
         }
     }
 }
 
 impl From<Box<dyn std::error::Error + Send + Sync>> for ShellError {
-    fn from(input: Box<dyn std::error::Error + Send + Sync>) -> ShellError {
+    fn from(error: Box<dyn std::error::Error + Send + Sync>) -> ShellError {
         ShellError::IOError {
-            msg: format!("{input:?}"),
+            msg: format!("{error:?}"),
         }
     }
 }
 
 impl From<super::LabeledError> for ShellError {
-    fn from(value: super::LabeledError) -> Self {
-        ShellError::LabeledError(Box::new(value))
+    fn from(error: super::LabeledError) -> Self {
+        ShellError::LabeledError(Box::new(error))
     }
 }